62  ANATOMY   FOK   NURSES.  [CHAP.  VI. 

The  muscles  of  the  back  are  disposed  in  five  layers,  one  be- 
neath another.  The  two  largest  and  most  superficial  are  the 
trapezius  and  the  latissimus  dorsi. 

The  trapezius  arises  from  the  middle  of  the  occipital  bone, 
and  from  the  spine  as  far  as  the  last  dorsal  vertebra.  From 
this  extended  line  of  origin  the  fibres  converge  to  their  in- 
sertion in  the  acromion  process  and  spine  of  the  scapula. 
The  latissimus  dorsi  arises  from  the  last  six  dorsal  vertebrae, 
and  through  the  medium  of  the  lumbar  aponeurosis,  from  the 
lumbar  and  sacral  part  of  the  spine  and  from  the  crest  of  the 
ilium.  The  fibres  pass  upwards  and  converge  into  a  thick,  nar- 
row band,  which  winds  around  and  finally  terminates  in  a  flat 
tendon,  which  is  inserted  into  the  front  of  the  hurnerus  just 
below  its  head. 

These  muscles  cover  nearly  the  whole  of  the  back ;  but  as 
they  act  upon  the  bones  of  the  upper  extremity,  they  are  often 
more  properly  reckoned  as  belonging  to  the  muscles  of  that 
region. 

The  muscles  of  the  thorax  are  chiefly  concerned  with  the 
movements  of  the  ribs  during  respiration.  They. are  the  inter- 
costals,  subcostals,  etc. 

The  chief  bulk  of  the  anterior  muscular  wall  of  the  chest  is 
made  up  of  the  pectoral  muscles,  which  arise  mainly  from  the 
front  of  the  sternum.  The  fibres  converging  form  a  thick  mass, 
which  is  inserted  by  a  tendon  of  considerable  breadth  into  the 
upper  part  of  the  humerus.  As  these  muscles  move  the  arm, 
they  are,  like  the  superficial  muscles  of  the  back,  usually  reck- 
oned among  the  muscles  of  the  upper  extremity.  Covering  the 
pectoral  muscles  is  a  superficial  fascia  (composed  of  connective 
tissue)  in  which  are  lodged  the  mammary  glands  and  a  variable 
amount  of  fat. 

The  muscular  walls  of  the  abdomen  are  mainly  formed  by 
three  layers  of  muscles,  the  fibres  of  which  run  in  different  direc- 
tions, those*  of  the  superficial  and  middle  layers  being  oblique, 
and  those  of  the  innermost  layer  being  transverse.  In  front, 
these  three  layers  of  muscles  are  replaced  by  tendinous  expan- 
sions or  aponeuroses,  which  meet  in  the  middle  line,  the  line  of 
union  giving  rise  to  a  white  cord-like  line,  the  linea  alba.  On 
each  side  of  this  line  the  fibres  of  a  straight  muscle,  the  rectus 
muscle,  extend  in  a  vertical  direction  between  the  tendinous 


PLATE  IV.  —  MUSCLES  OF  CHEST  AND  ABDOMEN.  55,  pectoral  muscle  :  44,  serratus 
magnus ;  34,  external  oblique ;  35,  rectus  abdominis,  the  external  layer  of  aponeurotic 
sheath  is  removed ;  38,  linea  alba ;  40,  aponeurosis. 

63 


UNIVERSITY  OF  CALIFORNIA 

MEDICAL  CENTER  LIBRARY 

SAN  FRANCISCO 


Gift  of 
Mrs.  Ginellc  Lemon 


TEXT-BOOK 


ANATOMY  AND  PHYSIOLOGY 


FOR   NURSES 


COMPILED  BY 

/ 

DIANA   CLIFFORD  \  gIMBER 

GEADUATE  OP  BELLEVUE  TRAINING  SCHOOL;  ASSISTANT -SUPERINTENDENT  NEW  YORK  CITY 

TRAINING   SCHOOL,    BLACKWELL'S   ISLAND,   N.  Y. ;   FORMERLY   ASSISTANT 

SUPERINTENDENT  ILLINOIS  TRAINING  SCHOOL,  CHICAGO,  ILL. 


gorft 
THE    MACMILLAN    COMPANY 

LONDON:  MACMILLAN  &  CO.,  LTD. 
1899 


All  rights  reserved 


COPYRIGHT,  1893, 
BY  MACMILLAN  AND   CO. 


Set  up  and  electrotyped  September,  1894.     Reprinted 
November,  1894;   February,  August,  1805  ;  January,  No- 
vember, 1896;  July,  December,  1897;  September,  1898; 
July,  1899. 


Nortooot) 
J.  S.  CushinR  &  Co.  -  Berwick  &  Smith 
Norwood  Mas*.  I'.S.A. 


Uetucateti 

TO    MY 
FRIEND,    SCHOOLMATE,    AND    SUPERINTENDENT 

ILoutse  Barcfje 

GRADUATE    OF   BELLEVUE    TRAINING   SCHOOL 
AND 

SUPERINTENDENT  NEW  YORK  CITY  TRAINING  SCHOOL 
BLACKWELL'S  ISLAND,  N.Y. 


The  following  illustrations  have  been  copied  from  Quain's 
"Anatomy"  and  Schafer's  "Essentials  of  Histology,"  and 
are  used  in  this  work  by  permission  of  the  authors  and  pub- 
lishers of  those  books,  viz. :  Figs.  4,  5,  8,  10,  12,  14,  51,  53,  64, 
69,  83,  86,  103,  110,  117,  121, 127,  128. 


PKEFACB. 


IN  preparing  the  following  pages  for  publication,  it  has  been 
my  endeavour  to  keep  the  fact  that  I  was  writing  for  nurses, 
constantly  in  mind.  So  far  as  I  know,  no  attempt  has  yet 
been  made  to  compile  a  text-book  on  anatomy  and  physiology 
for  the  use  of  nurses,  although  the  subject  is  more  or  less 
universally  and  systematically  taught  in  our  training  schools. 
During  several  years  I  have  spent  much  time  and  trouble 
in  preparing  notes  on  this  subject  for  class-teaching,  and  it 
was  suggested  to  me  that  if  these  notes  could  be  put  into 
shape,  they  might  prove  useful  in  our  schools.  The  scheme 
of  the  book  has  been  practically  worked  out  in  class-teaching, 
and  in  compiling  the  notes  from  standard  works  on  anatomy 
and  physiology,  I  have  sought  to  abstract  that  which  shall 
prove  valuable  and  interesting  to  the  nurse,  while  avoiding 
those  innumerable  and  minute  details  indispensable  to  the 
medical  student. 

On  first  glancing  through  the  following  pages,  it  may  be 
thought  that  the  structural  elements  of  the  tissues  have  been 
dwelt  upon  at  greater  length  than  is  at  all  necessary,  and 
that  the  whole  subject  has  been  thereby  made  unnecessarily 
difficult.  In  reply  to  which  I  can  only  say  that  after  repeated 
experiments  in  teaching,  this  method  has  gradually  revealed 
itself  to  me  as  the  most  effectual  one  for  making  the  subject 
intelligible,  and  I  have  found,  after  careful  instruction  in 
the  structure  of  the  tissues,  the  student  most  readily  under- 
stands the  functions  of  the  different  parts  of  the  body. 

It  is  always  well  to  bear  in  mind  that  the  primary  object  of 
educative  methods  is  to  enlarge  the  mental  capacity  of  the 


o 
vii 


vhi  PREFACE. 

student,  and  not  to  make  her  swallow  a  mass  of  undigested 
facts.  To  insist  upon  accuracy  of  statement;  to  enlarge  the 
pupil's  vocabulary;  to  train  her  to  trace  from  cause  to  effect 
in  different  conditions,  —  if  nothing  else  is  accomplished,  this 
is  a  great  deal,  and  will  make  a  nurse  of  distinctly  greater 
value  and  of  higher  grade,  than  one  whose  mind  has  not, 
with  all  her  training,  been  trained  to  think. 

It  seemed  best  to  arrange  the  book  in  chapters  rather 
than  in  lessons,  owing  to  the  difficulty  of  making  each  sub- 
ject of  an  equal  length ;  in  the  introductory  contents,  however, 
a  scheme  of  the  subject,  arranged  in  lessons  of  suitable  length, 
is  provided.  It  is,  perhaps,  superfluous  to  suggest  that  in 
making  use  of  the  text-book  for  class-teaching,  each  lesson 
should  be  illustrated  as  far  as  possible  by  anatomical  charts, 
skeleton  or  manikin,  and,  where  obtainable,  by  specimens  from 
the  human  subject. 

The  book  has  been  compiled  from  the  following  works : 
Quain's  "Anatomy,"  edited  by  E.  A.  Schafer,  F.R.S.,  and  Prof. 
G.  D.  Thane ;  Gray's  "  Anatomy,"  edited  by  T.  Pickering  Pick  ; 
"Text-book  of  Physiology,"  by  M.  Foster,  M.A.;  "Physiology 
and  Hygiene,"  by  T.  H.  Huxley,  F.R.S.,  and  D.  J.  Youmans, 
M.D. ;  "  Human  Physiology,"  by  John  C.  Dalton,  M.D. ;  "  The 
Human  Body,"  by  H.  Newell  Martin,  M.D. ;  Woods'  "House- 
hold Practice  of  Medicine,"  edited  by  Fred.  A.  Castle,  M.D. ; 
"The  Essentials  of  Histology,"  by  E.  A.  Schafer,  F.R.S. ; 
"Practical  Normal  Histology,"  by  F.  M.  Prudden,  M.D. 

I  am  specially  indebted  to  my  friend,  Louise  Darche,  for  invalu- 
able assistance.  Without  her  aid,  the  book  would  neither  have 
been  begun,  continued,  or  finished,  and  if  it  meets  the  require- 
ments of  our  schools,  it  will  be  largely  owing  to  her  hearty  co-oper- 
ation and  the  criticism  and  advice  given  by  her  in  every  page. 

NEW  YORK,  August  12,  1894. 


CONTENTS. 

ARRANGED   IN   CHAPTERS   AND   LESSONS. 


CHAPTER    I. 

PAGB 

(LESSON  I.)  Introductory  —  General  Outline  of  the  Body  ;  Different  Parts 

of  the  Body  ;  Structural  Elements  of  the  Tissues  ;  The  Cell          .        .        1 

CHAPTER   II. 

(LESSON  II.)  Origin  of  Tissues  ;  Epithelial  Tissues  ;  Stratified  ;  Transi- 
tional ;  Simple 8 

CHAPTER    III. 

(LESSON  III.)  Connective  Tissues :  Connective  Tissue  Proper  ;  Adipose  or 
Fat  Tissue  ;  Reticular  and  Lymphoid  Tissue.  —  (LESSON  IV.)  Carti- 
lage ;  Bone 13 

CHAPTER    IV. 

(LESSON  V.)  The  Skeleton  ;  Long  and  Short  Bones.  —  (LESSON  VI.)  Flat 

and  Irregular  Bones.  —  (LESSON  VII.)  General  Review  of  Boiies         .      23 

CHAPTER   V. 
(LESSON  VIII.)  The  Joints 47 

CHAPTER  VI. 

(LESSON  IX.)  Muscular  Tissues  ;  Striated  or  Striped  ;  Non-striated  or 
Plain  —  Attachment  of  Muscles  to  Skeleton. —  (LESSON  X.)  Prominent 
Muscles  of  the  Head  and  Trunk.  —  (LESSON  XI.)  Prominent  Muscles 
of  the  Limbs 52 

NOTE.  —  In  most  training  schools  in  America  instruction  in  class  is  given  from 
Oct.  1  to  June  1,  or  for  thirty-eight  consecutive  weeks:  the  lessons  in  this  text-book 
can  be  conveniently  mastered  in  the  first  year's  course,  taken  in  the  manner  indi- 
cated in  these  introductory  contents. 

ix 


LIST  OF  ILLUSTRATIONS. 


FIGURE  PAGE 

1.  Diagrammatic  Longitudinal  Section  of  the  Trunk  and  Head      .        .  2 

2.  Diagram  of  a  Cell        ..........  4 

3.  Consecutive  Stages  of  Cell-Division,  with  Indirect  Division  of  the 

Nucleus 6 

4.  Section  of  Stratified  Epithelium 9 

5.  Section  of  the  Transitional  Epithelium  lining  the  Bladder  ...  10 

6.  Simple  Pavement  Epithelium       ........  10 

7.  Simple  Columnar  Epithelium 11 

8.  Glandular  Epithelium,  with  the  Cells  set  round  a  Simple  Saccular 

Gland 11 

9.  Ciliated  Epithelium  from  the  Human  Trachea    .         .        .  .11 

10.  Subcutaneous  Areolar  Tissue  from  a  Young  Rabbit    ....  14 

11.  Fibrous  Tissue  from  the  Longitudinal  Section  of  a  Tendon        .        .  15 

12.  A  Few  Fat  Cells  from  the  Margin  of  a  Fat  Lobule     ....  17 

13.  Articular  Hyaline  Cartilage  from  the  Femur  of  an  Ox        ...  19 

14.  Transverse  Section  of  Compact  Tissue  (of  Humerus)          ...  21 

15.  The  Skeleton 24 

16.  The  Clavicle 25 

17.  The  Humerus 25 

18.  The  Ulna  and  Radius 26 

19.  Bones  of  the  Wrist  and  Hand 26 

20.  The  Femur 27 

21.  Bones  of  the  Right  Leg 28 

22.  Bones  of  the  Ankle  and  Foot 28 

23.  Occipital  Bone 29 

24.  Parietal  Bone 30 

25.  Frontal  Bone 31 

26.  Nasal  Bone 31 

27.  Lachrymal  Bone 31 

28.  Voraer 32 

29.  Scapula 32 

30.  Sternum 33 

31.  Os  Innominatum 34 

32.  Temporal  Bone 35 

33.  Sphenoid  Bone 36 

34.  Ethmoid  Bone      .                 36 

35.  Malar  Bone 37 

36.  Palate  Bone 37 

xiii 


xiv  LIST   OF   ILLUSTRATIONS. 

FIOURB  PAOB 

37.  Inferior  Turbinated  Bone 37 

38.  Superior  Maxillary  Bone      .        .         . 37 

39.  Inferior  Maxillary  Bone 38 

40.  Hyoid  Bone 38 

41.  A  Cervical  Vertebra 39 

42.  Side  View  of  Spinal  Column,  without  Sacrum  and  Coccyx         .        .  40 

43.  The  Skull 41 

44.  The  Skull  at  Birth 42 

45.  Male  Pelvis 43 

46.  Female  Pelvis «...  43 

47.  Thorax 44 

48.  A  Toothed  or  Dentated  Suture 47 

49.  A  Mixed  Articulation 49 

50.  A  Simple  Complete  Joint 48 

51.  Muscular  Fibre                              .     * 52 

62.  Fragments  of  Striped  Fibres  showing  a  Cleavage  in  Opposite  Direc- 

tions         ............  53 

63.  Wave  of  Contraction  passing  over  a  Muscular  Fibre  of  Dytiscus        .  54 

64.  Fibre-Cells  of  Plain  Muscular  Tissue  .......  55 

65.  Muscles  of  Right  Eyeball  within  the  Orbit 58 

66.  Muscles  of  Eyeball 58 

57.  Muscles  of  the  Tongue 60 

58.  Muscles  of  the  Arm 66 

69.    Muscles  in  Front  of  Forearm       ........  67 

60.  Muscles  of  the  Thigh 68 

61.  Muscles  of  the  Leg.     Superficial  View  of  the  Calf      ....  69 

62.  Red  and  White  Corpuscles  of  the  Blood 75 

63.  The  Heart  and  Lungs 82 

64.  Anterior  View  of  Heart,  dissected  after  long  Boiling,  to  show  the 

Superficial  Muscular  Fibres      ........  83 

65.  Right  Side  of  Heart 84 

60.    Left  Side  of  Heart 85 

67.  Section  of  Heart  at  Level  of  Valves 85 

68.  Structure  of  an  Artery 88 

69.  Part  of  a  Vein  laid  Open 90 

70.  Portion  of  Endothelium  of  Peritoneum        ......  91 

71  and  72.    The  Aorta 95 

7:;.    The  Carotid,  Subclavian,  and  Axillary  Arteries 06 

74.  Deep  Anterior  View  of  the  Arteries  of  the  Arm,  Forearm,  and  Hand  97 

75.  Iliac  and  Femoral  Arteries 100 

76.  View  of  Popliteal  Artery 101 

77.  Deep  View  of  the  Arteries  of  the  Back  of  the  Leg      ....  102 

78.  Anterior  View  of  Arteries  jof  the  Leg 102 

79.  Arteries  of  the  Foot 103 

80.  Sketch  of  the  Principal  Venous  Trunks 104 

81.  Superficial  Veins  of  Lower  Extremity          .        .         .        .         .         .  105 

W.    Diagram  of  Circulation 109 

8:).    Isolated  Capillary  Network  formed  by  the  Junction  of  Several  Hol- 

lowed-out  Cells,  and  containing  Coloured  Blood  Corpuscles  in  a 

Clear  Fluid  118 


LIST   OF   ILLUSTRATIONS. 


xv 


FIGURE  PAOB 

84.  A  Small  Portion  of  a  Lymphatic  Plexus 120 

85.  Lymphatics  and  Lymphatic  Glands  of  Axilla  and  Arm       .         .        .  124 

86.  Diagrammatic  Section  of  Lymphatic  Gland         .....  125 

87.  Vertical   Section   of  a  Portion  of  a  Peyer's  Patch,  with  Lacteal 

Vessels  injected 126 

88.  The  Mouth,  Nose,  and  Pharynx,  with  the  Commencement  of  Gullet 

and  Larynx 130 

89.  The  Larynx  as  seen  by  Means  of  the  Laryngoscope    .         .         .         .131 

90.  Front  View  of  Cartilages  of  Larynx 132 

91.  Two  Alveoli  of  the  Lung 133 

92.  Anterior  View  of  Lungs  and  Heart 134 

93.  Diagram  showing  the  Various  Forms  of  Secreting  Structures     .        .  143 

94.  An  Intestinal  Villus 146 

95.  The  Salivary  Glands 155 

96.  The  Mouth,  Nose,  and  Pharynx,  *  with  the  Larynx  and  Commence- 

ment of  Gullet,  seen  in  Section        .......  157 

97.  Vertical  and  Longitudinal  Section  of  Stomach  and  Duodenum  .        .  159 

98.  An  Intestinal  Villus 160 

99.  Section  through  the  Lymphoid  Tissue  of  a  Solitary  Gland  .         .        .161 

100.  Caecum,  showing  its  Appendix,  Entrance  of    Ilium,  and  Ileo-Csecal 

Valve 162 

101.  Posterior  View  of  Pancreas 163 

102.  Under  Surface  of  Liver 164 

103.  Diagrammatic  Representation  of  Two  Hepatic  Lobules       .        .         .  165 

104.  Section  of  Rabbit's  Liver,  Vessels  and  Bile  Ducts  injected         .         .  166 

105.  The  Renal  Organs  viewed  from  Behind 180 

106.  Section  through  the  Kidney 182 

107.  Vascular  Supply  of  Kidney 183 

108.  Plan  of  Blood- Vessels  connected  with  the  Tubules      ....  184 

109.  Diagram  of  the  Course  of  Two  Uriniferous  Tubules  ....  185 

110.  Section  of  Epidermis 189 

111.  Section  of  Skin  showing  Two  Papillae  and  Deeper  Layers  of  Epidermis  191 

112.  Piece  of  Human  Hair 192 

113.  Section  of  Skin  showing  the  Hairs  and  Sebaceous  Glands   .        .        .  193 

114.  Coiled  End  of  a  Sweat-Gland 194 

115.  Multi-polar  Nerve-Cell 200 

116.  Nerve-Fibres .        .201 

117.  Section  of  the  Internal  Saphenous  Nerve 202 

118.  Diagram  illustrating  the  General  Arrangement  of  the  Nervous  System  203 

119.  Side  View  of  the  Brain  and  Spinal  Cord  in  Place        .        .        .        .204 

120.  The  Base  of  the  Brain 205 

121.  Transverse  Sections  of  the  Spinal  Cord  at  Different  Levels         .         .  211 

122.  Base  of  Brain,  Spinal  Cord,  and  Spinal  Nerves 212 

123.  Sections  of  Spinal  Cord  and  Nerve-Roots 213 

124.  General  View  of  the  Sympathetic  System 214 

125.  Nerve  Ending  in  Muscular  Fibre  of  a  Lizard 215 

126.  Section  of  Skin,  showing  Tactile  Corpuscle  in  Papilla         .        .        .216 

127.  End-Bulbs  from  the  Human  Conjunctiva 217 

128.  The  Upper  Surface  of  the  Tongue 220 

129.  Vertical  Longitudinal  Section  of  Nasal  Cavity 222 


xvi  LIST   OF   ILLUSTRATIONS. 


130.  Semi-diagrammatic  Section  through  the  Right  Ear     .        .        .        .224 

131.  The  Left  Eyeball  in  Horizontal  Section  from  before  Back  .        .        .  228 

132.  Diagrammatic  Section  of  the  Human  Retina 230 

133.  Diagram  illustrating  Rays  of  Light  converging  in   (4)  a  Normal 

Eye,  (£)  a  Myopic  Eye,  and  (<7)  Hypermetropic  Eye    .        .        .  233 

134.  The  Lachrymal  Apparatus 235 

135.  Section  of  Female  Pelvis  showing  Relative  Portion  of  Viscera   .        .  238 

136.  The  Uterus  and  its  Appendages  ........  240 

137.  Section  of  an  Ovary 242 


PLATES. 

PLATE  PAGB 

I.  Forms  of  Muscles  and  Tendons 57 

II.   Muscles  of  Face,  Head,  and  Neck 59 

III.  Muscles  of  Back 61 

IV.  Muscles  of  Chest  and  Abdomen 63 

V.   The  Abdominal  Aorta  and  its  Contents 99 

VI.    Plan  of  Foetal  Circulation 116 

VII.   Regions  of  the  Abdomen  and  their  Contents 154 


TEXT-BOOK 

OF 

ANATOMY  AND  PHYSIOLOGY  FOE  NUESES. 

CHAPTER  I. 

INTRODUCTORY.  —  GENERAL  OUTLINE  OF  THE  BODY.  —  DIFFER- 
ENT PARTS  OF  THE  BODY.  —  STRUCTURAL  ELEMENTS  OF 
THE  TISSUES.  — THE  CELL. 

Introductory.  —  In  looking  upon  the  fully  developed  human 
body  we  are  impressed  with  the  complexity  of  its  structure,  the 
perfection  of  its  mechanism,  the  mysteriousness  of  its  life.  To 
learn  to  understand  something  of  this  structure,  this  mechan- 
ism, this  life,  is  one  of  our  most  imperative  duties  as  nurses;  for 
how  can  we  appreciate  the  significance  of  abnormal  functions, 
and  the  seriousness  of  diseased  conditions,  unless  we  are  ac- 
quainted with  the  normal  functions  of  the  body,  and  have  some 
knowledge  of  healthy  bodily  conditions  ? 

In  the  following  pages  we  propose  to  give  a  description  of 
the  structure,  of  the  position,  and  of  the  special  work  or  func- 
tion of  each  part  of  the  body.  We  have  dwelt  specially  upon 
the  structure  of  the  different  parts,  believing  that  any  correct 
understanding  of  the  bodily  functions  must  be  preceded  by  a 
certain  amount  of  knowledge  concerning  the  structure  of  the 
organs  performing  these  functions. 

Before  taking  up  the  subject  in  detail  it  is  well,  first  of  all, 
to  get  a  general  idea  of  the  main  divisions,  and  the  position  of 
the  different  parts,  and  we  shall  therefore  begin  our  considera- 
tion of  the  body  with  an  outline  of  its  structure. 

General  outline  of  the  body.  —  It  is  readily  seen  that  the  human 
body  is  separable  into  trunk,  head,  and  limbs ;  the  trunk  and 
head  are  cavities,  and  contain  the  internal  organs  or  viscera, 

B  1 


ANATOMY   FOK   NUKSES. 


[CHAP.  I. 


while  the  limbs  are  solid  or  semi-solid,  contain  no  viscera,  and 
are  merely  appendages  of  the  trunk.  The  limbs  or  extremities, 
upper  and  lower,  are  in  pairs,  and  bear  a  rough  resemblance  to 
one  another,  the  shape  of  the  bones,  and  the  disposition  of  the 
muscles  in  the  thigh  and  arm,  leg  and  forearm,  ankle  and  wrist, 
foot  and  hand,  being  very  similar. 

The  trunk  and  head  contain  two  main  cavities,  and  looking 
at  the  body  from  the  outside  we  should  naturally  imagine  that 
these  two  cavities  were  the  cavity  of  the 
head  and  the  cavity  of  the  trunk,  respec- 
tively. If,  however,  we  divide  the  trunk 
and  head  lengthwise  into  two  halves,  by 
cutting  them  through  the  middle  line 
from  before  backwards,  we  find  the  trunk 
and  head  are  divided  by  the  bones  of  the 
spine  into  back  and  front  cavities,  and 
not  into  upper  and  lower  (vide  diagram). 
The  dorsal  or  back  cavity  is  a  com- 
plete  bony  cavity,  and  is  formed  by  the 
vertebrae  (bones  of  the  spine)  and  of  the 
bones  of  the  skull.  It  may  be  subdi- 
vided into  the  spinal  canal,  containing 
the  spinal  cord,  and  into  the  cranial  cav- 
ity, which  is  merely  an  enlargement  of 
the  spinal  canal,  and  contains  the  brain. 
Connected  with  the  dorsal  cavity  are  the 
FIG.  i.  —  DIAGRAMMATIC  two  small  orbital  cavities  containing  the 

LONGITUDINAL  SECTION  OF         f  {  }  t 
THE  TRUNK  AND  HEAD.  1,1,    & 

the  dorsal  cavity;  a,  the       The  ventral  or  front  cavity  is  not  a 
'omplete  bony  cavity,  part  of  its  walls 


bodies  of  the  vertebrae  form-  being  formed  of  muscular  and  other  tis- 

in-    the   partition    between  ...                                                    ,111 

the  dorsal  and  ventral  cavi-  sue  5   ^  ^  much  larger  than  the  dorsal 

ties;  2,  2,  the  ventral  cavity,  cavity,  and  may  be  subdivided  into  the 

subdivided  into  thoracic  cav-  *\          ,  ,        .      ,            ,         ,    . 

ity  (d),  abdominal  cavity  thoracic,  abdominal,  and  pelvic  cavities. 

(e)  and  pelvic  cavity  (/);  Th    thoracic  cavity,  or  chest,  contains  the 

y,  the  nasal   cavity;    h,  the  J 

month,   or   bnccai   cavity,  trachea   or  windpipe,  the  lungs,   gullet, 


heart,  and  the  great  vessels  springing 
the  whole  length  of  the  ven-  from,  and  entering  into,  the  heart.  The 

abdominal  cavity  contains  the  stomach, 
liver,  gall-bladder,  pancreas,  spleen,  kidneys,  small  and  large 


CHAP.  I.]     DIFFERENT   PARTS   OF   THE   BODY.  3 

intestines,  etc.  The  pelvic  cavity  contains  the  bladder,  rectum, 
and  generative  organs.  Connected  with  the  upper  part  of  the 
ventral  cavity  are  two  small  cavities,  the  buccal  cavity,  or  mouth, 
containing  the  tongue,  teeth,  salivary  glands,  etc.,  and  the  nasal 
cavity,  containing  the  organ  of  smell. 

Different  parts  of  the  body.  —  In  speaking  of  the  different  parts 
of  the  body,  we  usually  call  each  part  an  organ,  and  we  may  say 
that  the  human  body  is  made  up  of  organs,  each  organ  being 
adapted  to  the  performance  of  some  special  work  or  function. 
Thus  the  lungs  are  organs  specially  adapted  for  performing 
the  function  of  respiration,  the  bones  are  organs  adapted  for 
support  and  locomotion,  the  kidneys  for  secreting  urine,  etc. 

Every  part  or  organ,  when  separated  into  minute  fragments, 
is  found  to  consist  of  certain  textures  or  tissues.  When  the 
body  is  thus  separated  or  dissected,  and  analyzed  by  the  aid  of 
the  microscope,  we  find  that  the  number  of  distinct  tissues  is 
comparatively  small,  and  some  of  these  again,  although  at  first 
sight  apparently  distinct,  yet  have  so  much  in  common  in  their 
structure  and  origin  one  with  another,  that  the  number  becomes 
still  further  reduced,  until  we  can  only  distinguish  four  distinct 
tissues,  viz. :  — 

The  epithelial  tissues.  The  muscular  tissues. 

The  connective  tissues.  The  nervous  tissues. 

Particles  met  with  in  the  fluids  of  the  body,  such  as  the  little  bodies  or  cor- 
puscles in  the  blood  and  lymph,  are  also  reckoned  among  these  elementary 
tissues. 

Some  organs  are  formed  of  a  combination  of  several  of  the 
above  tissues ;  others  contain  only  one  or  two.  Thus  the 
muscles  are  made  up  almost  entirely  of  muscular  tissue  with 
only  a  small  intermixture  of  connective  tissue,  blood-vessels, 
and  nerves ;  whilst  the  ligaments  or  sinews  are  composed 
wholly  of  a  variety  of  connective  tissue. 

On  the  other  hand,  there  are  certain  organs  or  parts  of  the 
body  not  in  themselves  distinguished  by  the  preponderance  of 
any  tissue.  Such  are  :  — 

Blood-vessels.  Synovial  membranes. 

Lymphatic  vessels.  Mucous  membranes. 

Lymphatic  glands  and  bodies  Secreting  glands. 

of  like  structure.  Integument  or  skin. 
Serous  membranes. 


4  ANATOMY   FOR   NUKSES.  [CHAP.  I. 

Thus,  though  we  may  say  the  greater  bulk  of  the  body  is  made 
up  of  a  combination  of  four  distinct  tissues, — the  epithelial, 
connective,  muscular,  and  nervous,  —  there  are  parts  in  which 
these  tissues  are  so  intimately  mixed  that  we  cannot  distinguish 
any  distinct  variety,  and  we  are  therefore  obliged  to  class  them 
by  themselves. 

Structural  elements  of  the  tissues.  —  When  any  tissue  is  sep- 
arated by  the  aid  of  the  microscope  into  its  simplest  parts,  such 
parts  are  termed  the  structural  elements  of  the  tissue.  The 
simplest  structural  element  of  every  tissue  is  a  cell  or  fibre,1 
and  however  diversified  the  tissues  of  the  body  may  appear  to 
be,  they  all  originate  as  collections  of  cells.  All  the  varied 
activities  of  the  body  are  the  result  of  the  activity  of  the  cells 
which  compose  it,  and  it  is  very  desirable,  owing  also  to  their 
being  the  foundation  of  all  structure  (the  bricks,  as  it  were,  out 
of  which  the  tissues  are  built),  that  we  early  acquire  some  defi- 
nite conception  of  these  tiny  elementary  bodies. 

The  cell. — A  cell   is   a  minute  portion  of  living  substance 
called  protoplasm,  which  is  sometimes 
enclosed  by  a  cell   membrane,  and  al- 
ways contains  a  vesicle  which  is  known 
^  as  the  nucleus. 

Up  to  1865  it  was  universally  believed 
• — 2?*   that  protoplasm  had  no  definite  parts, 
or,  in  other  words,  was  structureless ; 
A  but>  whei\  examined  under  the  highest 
CELL,    n,  nucleus ;  p,  proto-  microscopical   power,  it  appears  as  an 

exceedingly   fine    network    of   delicate 

fibres.  The  width  of  the  meshes  varies  to  some  extent ;  some- 
times they  are  narrow  and  close,  and  sometimes  wider  and  more 
open.  The  interspaces  are  filled  with  a  clear  soft  semi-fluid 
substance  and  minute  particles  or  granules  of  variable  size.  The 
microscope  can  tell  us  little  more  than  this,  though  there  are  good 
grounds  for  supposing  that  there  is  structure  that  cannot  be 
directly  observed.  We  have  to  turn  to  the  chemical  nature 
of  protoplasm  for  light  as  to  the  cause  of  its  remarkable  prop- 
erties. 

All  matter  of  whatever  kind  is  made  up  of  little  particles  or 
atoms,  so  small  that  they  are  perfectly  invisible  to  the  human 
1  A  fibre  is  merely  a  modified  cell. 


CHAP.  I.]  THE   CELL.  5 

eye  even  when  aided  by  all  the  appliances  of  optical  science, 
and  it  is  only  when  a  number  of  these  atoms  unite  into  one 
body  that  they  become  visible.  Every  little  piece  of  matter 
which  we  can  see  is  built  up  of  thousands,  or  rather  millions,  of 
these  atoms.  There  are  many  different  kinds  of  atoms.  Thus 
we  have  carbon,  hydrogen,  oxygen,  and  other  kinds,  each  having 
its  own  particular  weight,  and  probably  its  own  particular  size 
and  shape.  They  combine  by  mutual  attraction,  which  in  some 
cases  we  call  cohesion,  and  in  others  chemical  affinity,  accord- 
ing as  the  atoms  are  of  the  same  or  of  different  kinds.  In  this 
way  an  endless  variety  of  structures  may  be  built  up.  These 
structures  may  be  stable  and  solid,  the  myriads  of  atoms  com- 
posing them  cohering  so  firmly  together  that  it  is  almost  impos- 
sible to  separate  them  ;  or  they  may  be  very  unstable,  or  complex, 
the  particles  composing  them  being  of  many  different  kinds  and 
sizes,  held  together  in  the  loosest  fashion,  and  ready  to  fall  apart 
at  the  slightest  touch.  Again,  we  may  have  many  structures 
varying  in  stability  between  these  two  extremes. 

Protoplasm  is  a  highly  complex  structure,  and  its  chemical 
equilibrium  is  so  unstable  that  it  is  ready  to  break  down  at  the 
least  touch.  It  is  extremely  sensitive  to  any  outside  stimulus. 
Slight  influences  cause  it  to  alter  its  shape,  move,  and  exhibit 
other  phenomena;  these  phenomena  being  mainly  due  to  the 
inter-action  of  the  chemical  affinities  of  which  it  is  composed. 

During  the  life  of  a  cell  its  protoplasm  is  constantly  under- 
going changes,  the  chief  of  which  may  be  enumerated  as 
follows :  — 

(1)  All  protoplasm  coming  in  contact  with  oxygen  absorbs 
it  and  combines  with  it.      Whenever  this  combination   takes 
place,  a  certain  amount  of  the  protoplasm  is  burned  or  oxidized, 
and  as  a  result  of  this  oxidation  heat  and  other  kinds  of  energy 
are  produced,  and  carbonic  acid  evolved. 

(2)  All  protoplasm  is  able  to  take  into  itself,  and  eventually 
convert  into  its  own  substance,  material  that  is  non-living ;  this 
material  or  food  is  generally  supposed  to  be  a  compound  chem- 
ical substance  called  proteid,  which  is  a  combination  of  nitrogen, 
carbon,  oxj^gen,  and  hydrogen.      In  this  way  the   protoplasm 
may  increase  in  amount,  or  in  other  words  the  cell  may  grow; 
but  if  the  amount  of  protoplasm  does  not  permanently  increase, 
this  is  due  to  the  fact  that  just  as  much  protoplasm  is  being 


6 


ANATOMY   FOB   NURSES. 


[CHAP.   I. 


broken  down  by  the  process  of  oxidation,  and  removed  from  the 
cell,  as  is  added  by  the  process  of  assimilation.  Chemical 
changes  which  involve  the  building  up  of  living  material  within 
the  cell  have  received  the  general  name  of  anabolic  changes ; 
those,  on  the  other  hand,  which  involve  the  breaking  down  of 

such  material  into  other  and 
simpler  products,  are  known 
as  katabolic  changes :  while  the 
sum  of  all  the  ana-  and  kata- 
bolic changes  which  are  pro- 
ceeding within  the  cell  are 
spoken  of  as  the  metabolism  of 
a  cell.  These  chemical  changes 
are  always  more  marked  as  the 
activity  of  the  cell  is  promoted 
by  warmth,  electrical  or  other 
stimulation,  the  action  of  cer- 
tain drugs,  etc. 

(3)  The  most  obvious  phys- 
ical changes  which  can  be  seen 
in  living  protoplasm,  by  the  aid 
of  the  microscope,  are  those 
which  are  termed  "amoeboid." 
This  term  is  derived  from  the 
fresh  water  amoeba,  which  has 
long  been  observed  to  exhibit 
spontaneous  changes  of  form, 
accompanied  by  a  flowing  of  its 
soft  semi-fluid  substance.  By 
virtue  of  this  property,  the  cells 

FIG.  ?>.—  A  TO  tf,  CONSECUTIVE  STAGES   can  move  from  one  place  to  an- 
OF  CELL-DIVISION,  WITH  INDIRECT  DIVIS-        .  TJ,  .    .  ,,     , 

ION  OF  THE  NUCLEUS.    (Diagrammatic.)     other.     It  one  ot  these  cells  be 

observed  under  a  high  power 

of-ii  microscope,  it  will  be  seen  gradually  to  protrude  a  portion 
of  its  protoplasm  ;  this  protrusion  extends  itself,  and  the  main 
part  or  body  of  the  cell  passes  by  degrees  into  the  elongated 
protrusion.  By  a  repetition  of  this  process,  the  cell  may  glide 
slowly  away  from  its  original  situation  and  move  bodily  along 
the  field  of  the  microscope,  so  that  an  actual  locomotion  takes 
place.  When  the  surface  of  these  free  cells  comes  in  contact 


CHAP.  L]  THE   CELL.  7 

with  any  foreign  particle,  the  protoplasm,  by  virtue  of  its  amo3- 
boid  movements,  tends  to  flow  round  and  enwrap  the  particles, 
and  particles  thus  enwrapped  or  incepted  may  then  be  conveyed 
by  the  cell  from  one  place  to  another. 

The  nucleus.  —  The  nucleus  of  a  cell  is  directly  concerned  in 
the  reproduction  and  division  of  the  cells.  In  dividing,  the 
nucleus  passes  through  a  series  of  remarkable  changes,  which 
are  too  complicated  to  be  studied  here.  (See  Fig.  3.)  The 
result  of  these  changes  is  that  either  directly  or  indirectly  the 
nucleus  splits  into  two,  the  protoplasm  divides  and  arranges 
itself  around  the  new  nuclei ;  these  daughter  cells  soon  grow  to 
the  size  of  the  parent  cell,  and  division  of  these  and  consequent 
multiplication  may  proceed  with  great  rapidity. 

To  sum  up:  The  cell  assimilates,  is  continually  building 
itself  up,  and  replenishing  its  store  of  energy,  is  as  continually 
breaking  down  into  simpler  products,  with  a  setting  free  of 
energy ;  it  grows ;  it  moves ;  it  reproduces  itself  —  in  other 
words,  it  is  alive  and  is  the  basis  of  all  life. 


CHAPTER   II. 

ORIGIN  OF  TISSUES.  —  EPITHELIAL  TISSUES :  STRATIFIED,  TRAN- 
SITIONAL,   SIMPLE. 

Origin  of  tissues.  —  In  the  first  chapter  we  stated  that  the  body 
is  made  up  of  different  parts  or  organs,  each  having  some 
special  work  to  do;  each  part  is  made  up  of  tissues,  of  which 
there  are  four  distinctive  kinds ;  each  tissue  is  made  up  of 
structural  elements,  cells  and  fibres ;  and  finally,  each  fibre 
being  a  modified  cell,  the  cell  is  the  basis  of  all  the  bodily 
structures. 

Thus,  in  the  early  embryo,  the  whole  body  is  an  agglomera- 
tion of  cells.  These  have  all  been  formed  from  the  ovum  or 
egg-cell,  which  divides  into  two  cells;  these  again  into  two, 
and  so  on  until  numbers  of  cells  are  produced.  Eventually 
these  cells  arrange  themselves  in  the  form  of  a  skin  or  mem- 
brane which  is  composed  of  three  layers.  These  layers  are 
known  respectively  as  the  epiblast,  or  upper  layer;  the  meso- 
blast,  or  middle  layer;  the  hypollast,  or  under  layer.  The 
epiblast  is  supposed  to  give  rise  to  the  nervous  tissue  and  most 
of  the  epithelial  tissue ;  the  mesoblast  to  the  connective  and 
muscular  tissues;  the  hypoblast  to  the  rest  of  the  epithelial 
tissue.  Of  these  tissues,  the  epithelial  is  the  simplest,  and  most 
nearly  allied  to  the  primitive  tissue,  and  will  first  engage  our 
attention. 

Epithelial  tissue.  —  Epithelial  tissue  is  composed  entirely  of 
cells  united  together  by  cohesive  matter.  The  cells  are  gener- 
ally so  arranged  as  to  form  a  skin  or  membrane,  covering  the 
external  and  internal  surfaces  of  the  body.  This  membrane  is 
seen  when  the  skin  is  blistered,  the  thin  and  nearly  transparent 
membrane  raised  from  the  surface  being  epithelial  tissue  —  in 
this  situation  called  epidermis,  because  it  lies  upon  the  surface 

8 


CHAP.  II.]  EPITHELIAL   TISSUE.  9 

of  the  true  skin.  In  other  situations,  epithelial  tissue  usually 
receives  the  general  name  of  epithelium. 

Classification.  —  We  may  classify  the  varieties  of  epithelium 
according  to  the  shape  of  the  cells  which  compose  them,  or 
according  to  the  arrangement  of  these  cells  in  layers.  Adopt- 
ing the  latter  and  simpler  classification,  we  distinguish  three 
main  varieties:  the  stratified,  consisting  of  many  layers;  the 
transitional,  consisting  of  two  or  three  layers;  the  simple,  con- 
sisting of  a  single  layer  of  cells. 

1.  Stratified  epithelium.  —  The  cells  composing  the  different 
layers  of  stratified  epithelium  differ  in  shape.  As  a  rule,  the 


FIG.  4.  —  SECTION  OF  STRATIFIED  EPITHELIUM,  c,  lowermost  columnar  cells; 
P,  polygonal  cells  above  these ;  fl,  flattened  cells  near  the  surface.  Between  the 
cells  are  seen  intercellular  channels,  bridged  over  by  processes  which  pass  from  cell 
to  cell. 

cells  of  the  deepest  layer  are  columnar  in  shape ;  the  next, 
rounded  or  many-sided,  whilst  those  nearest  the  surface  are 
always  flattened  and  scale-like,  the  protoplasm  of  the  cell  being 
finally  converted  into  a  horn-like  substance.  The  deeper  soft 
cells  of  a  stratified  epithelium  are  continually  multiplying  by 
cell-division,  and  as  the  new  cells  which  are  thus  produced 
in  the  deeper  parts  increase  in  size,  they  compress  and  push 
outwards  those  previously  formed.  In  this  way  cells  which 
were  at  first  deeply  seated  are  gradually  shifted  outwards  and 
upwards,  growing  harder  as  they  approach  the  surface.  The 
older  superficial  cells  are  being  continually  rubbed  off  as  the 
new  ones  continually  rise  up  to  supply  their  places. 

Stratified  epithelium  covers  the  anterior  surface  of  the  eye, 
lines  the  mouth,  the  chief  part  of  the  pharynx,  the  gullet,  the 
vagina,  and  part  of  the  uterus,  but  its  most  extensive  distribu- 
tion is  over  the  surface  of  the  skin,  where  it  forms  the  epider- 
mis. Wherever  a  surface  is  liable  to  abrasion  we  find  stratified 


10  ANATOMY   FOR   NURSES.  [CHAP.  IL 

scaly  epithelium,  and  we  may  therefore  classify  it  as  a  protec- 
tive epithelium. 

2.   Transitional  epithelium.  —  This  is  a  modification  of  strati- 
fied epithelium,  consisting  only  of  two  or  three  layers  of  cells. 


FIG.  5. —  SECTION  OF  THE  TRANSITIONAL  EPITHELIUM  LINING  THE  BLADDER. 
(Highly  magnified.)  (E.A.  S.)  a,  superficial;  b,  intermediate ;  c,  deep  layer  of  cells. 

The  superficial  cells  are  large  and  flattened,  having  on  their 
under  surface  depressions  into  which  fit  the  larger  ends  of  the 
pear-shaped  cells  which  form  the  next  layer.  Between  the 
tapering  ends  of  these  pear-shaped  cells  are  one  or  two  layers 
of  smaller,  many-sided  cells,  the  epithelium  being  renewed  by 
division  of  these  deeper  cells.  This  kind  of  transitional  epithe- 
lium lines  the  bladder  and  ureters. 

3.  Simple  epithelium.  —  This  is  composed  of  a  single  layer  of 
cells.  The  cells  forming  single  layers  are  of  distinctive  shape, 
and  have  distinctive  functions  in  different  parts  of  the  body. 
The  chief  varieties  are  the  pavement,  col- 
umnar, glandular,  and  ciliated. 

In  simple  pavement  epithelium  the  cells 
form  flat,  many-sided  plates  or  scales,  which 
fit  together  like  the  tiles  of  a  mosaic  pave- 
ment. It  forms  very  smooth  surfaces,  and 

FIG.  (I. —  SIMPLE  PAVE-  ,.  ,,         , 

MENT  EPITHELIUM,  a,  lmes  the  heart,  blood-vessels,  and  lym- 
from  a  serous  membrane;  phatics ;  the  mammary  ducts,  the  serous 

/',  from  ;i  blood-vessel.  .    . 

cavities,  etc. 

The  columnar  epithelium  is  a  variety  of  simple  epithelium  in 
which  the  cells  have  a  prismatic  shape,  and  are  set  upright  on 
the  surface  which  they  cover.  In  profile  these  cells  look  some- 
what like  a  close  palisade,  their  edges,  however,  being  often 
irregular  and  jagged,  especially  where  free  or  "  wander-cells  " 


CHAP.  II.] 


EPITHELIAL   TISSUE. 


11 


squeeze  in  between  them.     Columnar  epithelium  is  found  in  its 
most  characteristic  form  lining  the  mucous 
membrane  of  the  intestinal  canal. 

Glandular  epithelium  is  found  in  the  re- 
cesses of  secreting  glands.  The  cells  are  of 
many  different  shapes,  and  are  usually  set 
round  a  tubular  or  saccular  cavity,  into 


FIG.  7. —  SIMPLE  COL- 
UMNAR EPITHELIUM,  a, 
the  cells ;  b,  intercellular 

which  the  secretion  is  poured.     The  proto-  fubstanc«  Between  the 

lower  end  of  cells. 

plasm  of  these  cells  is  generally  filled  by 

the  materials  which  the 


gland 
secretes. 

In  ciliated  epithelium  the  cells, 
which  are  generally  columnar  in 
shape,"  bear  at  their  free  extrem- 
ities little  hair-like  processes 
which  are  agitated  incessantly 
with  a  lashing  or  vibrating  mo- 
tion. These  minute  and  delicate 
processes  are  named  cilia,  and 
may  be  regarded  as  active  prolon- 
gations of  the  cell-protoplasm. 

FIG.   8.  -  GLANDULAR   EPITHELIUM,    The  maimer  in  which  cilia  move 
WITH  THE  CELLS  SET  ROUND  A  SIMPLE 

SACCULAR  GLAND.    (Highly  magnified.)  is  best  seen  when  they  are  not 

acting  very  quickly.  The  mo- 
tion of  an  individual  cilium  may  be  compared  to  the  lash-like 
motion  of  a  short-handled 
whip,  the  cilium  being  rap- 
idly bent  in  one  direction. 
The  motion  does  not  involve 
the  whole  of  the  ciliated  sur- 
face at  the  same  moment, 
but  is  performed  by  the  cilia 
in  regular  succession,  giv- 
ing rise  to  the  appearance  of 
a  series  of  waves  travelling 
along  the  surface  like  the 
waves  caused  by  the  wind 
in  a  field  of  wheat.  When 
they  are  in  very  rapid  action,  their  motion  conveys  the  iilea  of 
swiftly  running  water. 


FIG>  9.  — CILIATED  EPITHELIUM  FROM  THK 
HUMAN  TRACHEA.     (Highly   magnified.)    a, 

large  ciliated  cell  ;  d,  cell,  with  two  nuclei. 


12  ANATOMY  FOR   NURSES.  [CHAP.  II. 

Cilia  have  been  shown  to  exist  in  almost  every  class  of  ani- 
mal, from  the  highest  to  the  lowest.  In  man  their  use  is  to 
impel  secreted  fluids,  or  other  matters,  along  the  surfaces  to 
which  they  are  attached;  as,  for  example,  the  mucus  of  the 
trachea  and  nasal  chambers,  which  they  carry  towards  the  out- 
let of  these  passages. 

Ciliated  epithelium  is  found  in  the  air  passages,  the  genera- 
tive organs,  ventricles  of  the  brain,  and  central  canal  of  the 
spinal  cord. 

To  recapitulate:  The  most  important  situations  in  which  a 
covering  or  lining  of  epithelial  tissue  is  found  in  the  body 
are :  — 

1.  On  the  surface  of  the  integument,  or  external  skin. 

2.  On  mucous  membranes,  or  internal  skin. 

3.  On   the  inner  surface  of   serous  membranes,  and  on  the 
inner  surface  of  the  heart,  blood-vessels,  and  lymphatics. 

4.  Lining   the  ventricles  or  cavities   of  the  brain,  and   the 
central  canal  of  the  spinal  cord. 

Some  varieties  of  epithelium  are  specially  modified  to  form 
protective  membranes ;  others  to  elaborate  or  make  secretions ; 
others,  again,  to  form  smooth  linings  for  opposing  surfaces ; 
and  yet  others  to  keep  the  surfaces  they  cover  clean,  by  sweep- 
ing outwards  material  that  would  otherwise  accumulate,  and 
clog  important  passages. 

The  hairs,  nails,  and  the  enamel  of  the  teeth,  are  modifica- 
tions of  epithelial  tissue. 


CHAPTER   III. 

CONNECTIVE  TISSUES:  CONNECTIVE  TISSUE  PROPER,  ADIPOSE 
OR  FAT  TISSUE,  RETICULAR  AND  LYMPHOID  TISSUE,  CAR- 
TILAGE, BONE. 

FOLLOWING  the  classification  of  tissues  we  have  adopted,  the 
next  group  of  tissues  to  be  studied  is  that  known  as  the  con- 
nective tissue  group.  This  includes  :  — 

Connective  tissue  proper. 
Adipose  or  fat  tissue. 
Reticular  and  lymphoid  tissue. 
Cartilage. 
Bone. 

These  tissues  differ  considerably  in  their  external  character- 
istics, but  are  alike  in  that  they  all  serve  to  connect  and  support 
the  other  tissues  of  the  body ;  they  tend  to  pass  imperceptibly 
the  one  into  the  other ;  there  are  many  points  of  similarity 
between  the  cells  which  occur  in  them,  and  we  may,  therefore, 
reasonably  group  them  together. 

When  connective  tissue  first  begins  to  be  formed  as  a  distinc- 
tive tissue,  the  cells  which  are  set  apart  to  form  it  are  round  in 
shape  and  loosely  packed  together;  later  these  cells  begin  to 
throw  out  branches  and  to  form  a  kind  of  network  with  open 
spaces.  In  these  open  spaces  a  semi-fluid  substance  is  deposited 
which  gradually  becomes  more  consistent,  and  in  this  substance 
is  developed  the  particular  fibres  which  are  the  chief  structural 
characteristics  of  connective  tissue  proper. 

Our  description  of  epithelial  tissue  was  briefly  this  :  a  skin 
or  membrane  formed  of  cells,  which  cells  may  be  of  a  variety  of 
shapes,  and  be  arranged  in  one  or  more  layers.  It  is  distinctly 
a  tissue  of  cells  with  very  little  of  what  we  call  intermediate  or 

13 


14 


ANATOMY   FOE,   NUKSES. 


[CHAP.  III. 


intercellular  substance  lying  between  the  cells.  Connective 
tissue  differs  from  epithelial  tissue  in  having  a  great  deal  of 
intercellular  substance  between  its  cells,  and  according  to  the 
manner  in  which  this  intercellular  substance  develops  do  we 
get  the  different  varieties  of  connective  tissue. 

Connective  tissue  proper.  —  There  are  three  modifications  of 
connective  tissue  proper ;  viz.  the  areolar,  the  fibrous,  and 
the  elastic. 

Areolar  tissue.  —  If  we  make  a  cut  through  the  skin,  and  pro- 
ceed to  raise  it  from  the  parts  lying  beneath,  we  observe  that  it  is 
loosely  connected  to  them  by  a  soft  filmy  substance  of  consider- 
able tenacity  and  elasticity.  This  is  areolar  tissue.  It  is  also 


Vic..  10.  — SUBCUTANEOUS  AREOLAR  TISSUE  FROM  A  YOUNG  RABBIT.  (Highly 
magnified.)  (E.  A.  S.)  The  white  libres  are  in  wavy  bundles,  the  elastic  fibres  form 
;tn  open  network,  p,  p,  vacuolated  cells;  g,  granular  cell;  c,  c,  branching  lamellar 
cells :  c',  a  flattened  cell,  of  which  only  the  nucleus  and  some  scattered  granules  are 
visible;/,  fibrillated  cell. 

found,  in  like  manner,  under  the  serous  and  mucous  mem- 
branes,1 and  serves  to  attacli  them  to  the  parts  which  they  line 
or  cover.  Proceeding  further,  we  find  this  areolar  tissue  lying 
between  the  muscles,  the  blood-vessels,  and  other  deep-seated 
parts ;  also  forming  investing  sheaths  for  the  muscles,  the 

1  These  membranes  line  the  internal  cavities  and  surfaces  of  the  body. 


CHAP.  111.]      CONNECTIVE   TISSUE   PKOPER.  15 

nerves,  the  blood-vessels,  and  other  parts.  It  both  connects 
and  insulates  entire  organs,  and,  in  addition,  performs  the  same 
office  for  the  finer  parts  of  which  these  organs  are  made  up.  It 
is  thus  one  of  the  most  general  and  most  extensively  distributed 
of  the  tissues.  It  is,  moreover,  continuous  throughout  the  body, 
and  from  one  region  it  may  be  traced  without  interruption  into 
any  other,  however  distanj, —  a  fact  not  without  interest  in  prac- 
tical medicine,  seeing  that  in  this  way  air,  water,  and  other 
fluids,  effused  into  the  areolar  tissue  ma}^  spread  far  from  the 
spot  where  they  were  first  introduced  or  deposited. 

Seen  with  the  naked  eye,  areolar  tissue  appears  to  be  com- 
posed of  a  multitude  of  fine  threads  and  films  crossing  irregu- 
larly in  every  imaginable  direction,  leaving  open  spaces  or 
areolce  between  them.  Viewed  with  the  microscope,  these 
threads  and  films  are  seen  to  be  principally  made  up  of  wavy 
bundles  of  exquisitely  fine,  transparent,  white  fibres,  and  these 
bundles  intersect  in  all  directions.  Mixed  with  the  white 
fibres  are  a  certain  number  of  elastic  fibres,  which  do  not  form 
bundles,  and  have  a  straight  instead  of  a  wavy  outline.  The 
cells  of  the  tissue,  of  which  there 

are    several    varieties,    lie    in    the  |  ,,       w ,, 

spaces    between    the    bundles    of  | 

fibres. 

On  comparing  the  areolar  tissue 
of  different  parts,  it  is  observed  in 
some  to  be  more  loose  and  open  in         £ 
texture ;  in  others,  more  close  and        jj 
dense,  according  as.free  movement,       fi 

or  firm  connection  between  parts  is       I  •  >,j 

to  be  provided  for.  / 

Fibrous  tissue.  —  Fibrous  tissue  is     / 
intimately  allied   in   structure    to 
the  areolar  tissue,  but  the  bundles    / 
of  white  fibres  cohere  very  closely,  (/'  "'  •(] 

and  instead  of  interlacing  in  every       FIG.  11.— FIBROUS  TISSUE,  FROM 

direction  run  for  the  most  part  in    THE  LONGITUDINAL   SECTION  OF  A 

TENDON.    (After  Gegenbauer.) 

only  one  or  two  directions,  and  thus 

confer  a  distinctly  fibrous  aspect  on  the  parts  which  they  com- 
pose. This  fibrous  tissue  is  met  with  in  the  form  of  ligaments, 
connecting  the  bones  together  at  the  joints,  and  in  the  form  of 


16  ANATOMY   FOE,   NURSES.  [CHAP.  III. 

sinews  or  tendons,  by  means  of  which  the  muscles  are  attached 
to  the  bones.  It  also  forms  fibrous  membranes  which  invest 
and  protect  different  parts  or  organs  of  the  body.  Examples 
of  these  are  seen  in  the  periosteum  and  perichondrium,  which 
cover  the  bones  and  cartilages,  and  in  the  dura  mater,  which 
lines  the  skull  and  protects  the  brain.  Fibrous  membranes, 
called  fascia;,  are  also  employed  to  envelop  and  bind  down  the 
muscles  of  different  regions,  of  which  the  great  fascia,  enclosing 
the  muscles  of  the  thigh  and  leg,  is  a  well-known  example; 
and,  under  the  name  of  aponeuroses,  serve  for  the  attachment  of 
muscles  in  various  parts  of  the  body.  It  thus  appears  that 
fibrous  tissue  presents  itself  in  the  form  of  strong  bands  or 
cords,  and  of  dense  sheets  or  membranes. 

Fibrous  tissue  is  white,  with  a  peculiarly  shining  silvery 
aspect.  It  is  exceedingly  strong  and  tough,  yet  perfectly 
pliant ;  but  it  is  almost  devoid  of  extensibility.  By  these  qual- 
ities it  is  admirably  suited  to  the  purposes  for  which  it  is  used 
in  the  human  frame.  By  its  inextensile  character,  and  by  its 
strength,  it  maintains  in  apposition  the  parts  which  it  connects, 
and  we  find  that  the  ligaments  and  tendons  do  not  sensibly 
yield  to  extension  in  the  strongest  muscular  efforts  ;  and  though 
they  sometimes  snap  asunder,  it  is  well  known  that  bones  will 
break  more  readily  than  tendons ;  and  the  fibrous  membranes  or 
aponeuroses  are  equally  strong,  tough,  and  unyielding. 

Elastic  tissue.  —  In  elastic  tissue  the  wavy  white  bundles  are 
comparatively  few  and  indistinct,  and  there  is  a  proportionate 
development  of  the  elastic  fibres.  When  present  in  large  num- 
bers they  give  a  yellowish  colour  to  the  tissue.  This  form  of 
connective  tissue  is  extensile  and  elastic  in  the  highest  degree, 
but  is  not  so  strong  as  the  fibrous  variety,  and  breaks  across  the 
direction  of  its  fibres  when  forcibly  stretched. 

It  occurs  in  its  most  characteristic  form  in  what  is  called 
the  ligamenta  subflava,  which  forms  an  elastic  band  between 
some  of  the  bones  of  the  spine.  Elastic  tissue  is  also  found  in 
the  walls  of  the  air  tubes ;  unites  the  cartilages  of  the  larynx  : 
and  enters  largely  into  the  formation  of  the  walls  of  the  blood- 
vessels, especially  of  the  arteries. 

These  three  varieties  of  connective  tissue  agree  closely  with 
one  another  in  elementary  structure.  It  is  the  different  ar- 
rangement of  the  cells  and  fibres,  and  the  relative  proportion  of 


CHAP.  Ill,]  ADIPOSE   TISSUE.  17 

one  kind  of  fibre  to  the  other,  that  gives  them  their  different 
characteristics :  the  interlacing  of  the  wavy  bundles  of  finest 
fibres,  giving  us  the  delicate  web-like  areolar  tissue ;  the  close 
packing  of  these  bundles,  giving  us  the  dense  opaque  fibrous 
membranes  and  bands;  and  the  preponderance  of  the  elastic 
fibres,  furnishing  the  extensile  elastic  tissue. 

This  connective  tissue  proper,  as  we  have  already  noted,  is 
used  for  purely  mechanical  purposes :  forming  inextensile  bands 
or  pulleys ;  strong  protective  membranes  ;  web-like,  binding,  and 
supporting  material ;  sheaths  of  varying  degrees  of  density ; 
elastic  bands  or  membranes ;  and  it  also  serves  to  carry  the 
blood-vessels,  lymphatics,  and  nerves  to  the  parts  which  it 
connects  and  covers. 

Adipose  tissue.  —  When  fat  first  begins  to  be  formed  in  the 
embryo,  it  is  deposited  in  tiny  droplets  in  some  of  the  cells 


FIG.  12.  — A  FEW  FAT-CELLS  FROM  THE  MARGIN  OF  A  FAT-LOBULE.  Very 
highly  magnified.  /.  g.  fat-globules  distending  a  fat-cell ;  n,  nucleus;  ni.  membran- 
ous envelope  of  the  fat-cell;  c,  capillary  vessel;  v,  veinlet;  c.  t.  connective-tissue 
cell;  the  fibres  of  the  connective  tissue  are  not  shown. 

of  the  areolar  connective  tissue ;  these  droplets  increase  in  size, 
and  eventually  run  together  so  as  to  form  one  large  drop 
in  each  cell.  By  further  deposition  of  fat  the  cell  becomes 
swollen  out  to  a  size  far  beyond  that  which  it  possessed  orig- 
inally until  the  protoplasm  remains  as  a  delicate  envelope  sur- 


18  ANATOMY   FOR  NURSES.  [CHAP.  III. 

rounding  the  fat  drop.  As  these  cells  increase  in  number  they 
collect  into  small  groups  or  lobules,  which  lobules  are  for  the 
most  part  lodged  in  the  meshes  of  the  areolar  tissue,  and  are 
also  supported  by  a  fine  network  of  blood-vessels.  This  fatty 
tissue  exists  very  generally  throughout  the  body,  accompanying 
the  still  more  widely  distributed  areolar  tissue  in  most,  though 
not  in  all,  parts  in  which  the  latter  is  found.  Still,  its  distribu- 
tion is  not  uniform,  and  there  are  some  situations  in  which  it 
is  collected  more  abundantly.  It  forms  a  considerable  layer 
underneath  the  skin,  in  the  subcutaneous  areolar  tissue ;  it  is 
collected  in  large  quantity  around  certain  internal  parts, 
especially  the  kidneys ;  it  is  seen  rilling  up  the  furrows  on  the 
surface  of  the  heart;  it  is  deposited  beneath  the  serous  mem- 
branes, or  is  collected  between  their  folds ;  collections  of  fat 
are  also  common  around  the  joints,  padding  and  filling  up 
inequalities;  and,  lastly,  the  fat  exists  in  large  quantities  in 
the  marrow  of  bones. 

Adipose  tissue,  unless  formed  in  abnormal  quantities,  confers 
graceful  outlines  upon  the  human  frame ;  it  also  constitutes  an 
important  reserve  fund,  by  storing  up  fatty  materials,  derived 
from  the  food  and  brought  to  it  by  the  blood,  in  such  a  form 
and  manner  as  to  be  readily  reabsorbed  into  the  circulation 
when  needed. 

Retiform  and  lymphoid  tissue.  —  These  tissues  closely  resemble 
the  areolar  variety  of  connective  tissue,  except  that  the  bundles 
of  fibrils  occurring  in  them  are  very  much  finer,  and  the  meshes 
of  the  open  and  fine  network  are  filled  with  fluid  and  with 
lymph  cells.  The  reticular  or  retiform  tissue  forms  the  whole 
framework  of  some  of  the  organs  of  the  body,  and  enters  largely 
into  the  formation  of  the  mucous  membranes.  The  lymphoid 
or  adenoid  tissue  composes  the  greater  part  of  the  lymphatic 
glands,  and  other  allied  structures,  and  is  found  also  in  some 
mucous  membranes.  These  tissues  will  be  more  fully  described 
in  connection  with  the  organs  in  which  they  are  found. 

Cartilage.  —  This  is  the  well-known  substance  called  "gristle." 
When  a  very  thin  section  is  examined  with  a  microscope,  it  is 
seen  to  consist  of  nucleated  cells  disposed  in  small  groups  in  a 
mass  of  intercellular  substance.  This  intercellular  substance 
is  sometimes  transparent,  and  to  all  appearances  homogeneous 
or  structureless ;  sometimes  dim  and  faintly  granular,  like 


CHAP.  III.] 


CARTILAGE. 


19 


ground  glass :  both  these  conditions  are  found  in  what  is  called 
^  true  "  or  hyaline  cartilage,  and  which  is  the  most  typical  form 
of  the  tissue.  There  is  another 
variety  of  cartilage  in  which  the 
intercellular  substance  is  every- 
where pervaded  with  fibres. 
When  the  fibres  are  of  the  white 
variety,  it  is  called  white  fibro- 
cartilaye;  when  they  are  elastic 
fibres,  it  is  called  yellow  or  elastic 
fibro-cartilage. 

Although  cartilage  can  be  read- 
ily cut  with  a  sharp  knife,  it  is 
nevertheless  of  very  firm  consist- 
ence, but  at  the  same  time  highly 
elastic,  so  that  it  readily  yields 
to  extension  or  pressure,  and  im- 
mediately recovers  its  original 
shape  when  the  constraining 
force  is  withdrawn.  By  reason 
of  these  mechanical  properties  it 
serves  important  purposes  in  the 
construction  of  some  parts  of  the 
body. 

Hyaline  cartilage  occurs  principally  in  two  situations ;  viz. 
covering  the  ends  of  the  bones  in  the  joints,  where  it  is  known 
as  articular  cartilage,  and  forming  the  rib  cartilages,  where  it  is 
known  as  costal  cartilage.  In  both  these  situations  the  carti- 
lages are  in  immediate  connection  with  bone,  and  may  be  said 
to  form  part  of  the  skeleton.  The  articular  cartilages,  in  cov- 
ering the  ends  or  surfaces  of  bones  in  the  joints,  provide  these 
harder  parts  with  a  thick,  springy  coating,  which  breaks  the 
force  of  concussion,  and  gives  ease  to  the  motion  of  the  joint. 
The  costal  cartilages,  in  forming  a  considerable  part  of  the 
solid  framework  of  the  thorax  or  chest,  impart  elasticity  to  its 
walls.  Hyaline  cartilage  also  enters  into  the  formation  of  the 
nose,  ear,  larynx,  and  windpipe.  It  strengthens  the  substance 
of  these  parts  without  making  them  unduly  rigid,  maintains 
their  shape,  keeps  open  the  passages  through  them  where  such 
exist,  and  gives  attachment  to  moving  muscles  and  connecting 
ligaments. 


\ 

J'.RKXAUDOT  E.SALLE 

FIG.  13.  —  ARTICULAR  HYALINE 
CARTILAGE  FROM  THE  FEMUR  OF  AN 
Ox.  s,  intercellular  substance;  p, 
protoplasmic  cell ;  n,  nucleus.  (Ran- 


20  ANATOMY   FOR   NUKSES.  [CHAP.  III. 

Elastic  or  yellow  fibro-cartilage  is  tougher  and  more  flexible 
than  hyaline  cartilage;  it  only  occurs  in  parts  of  the  throat 
and  ear. 

White  fibro-cartilage  is  found  wherever  great  strength  com- 
bined with  a  certain  amount  of  rigidity  is  required;  thus  we 
find  it  joining  bones  together,  the  most  familiar  instance  being 
the  flat  round  plates  or  disks  of  fibro-cartilage  connecting  the 
bones  of  the  spine  and  the  pubic  bones.  White  fibro-cartilage 
very  closely  resembles  white  fibrous  tissue. 

Cartilage  is  not  supplied  with  nerves,  and  very  rarely  with 
blood-vessels.  Being  so  meagrely  supplied  with  blood  the  vital 
processes  in  cartilage  are  very  slow,  and  when  a  portion  of  it  is 
absorbed  in  disease  or  removed  by  the  knife,  it  is  regenerated 
very  slowly.  A  wound  in  cartilage  is  usually  at  first  healed  by 
connective  tissue  proper,  which  may  or  may  not  become  grad- 
ually transformed  into  cartilage.  Nearly  all  cartilages  receive 
their  nourishment  from  the  perichondrium  which  covers  them, 
and  which  is  a  moderately  vascular  fibrous  membrane. 

Bone.  —  Bone  is  a  connective  tissue  in  which  the  intercellular 
or  ground  substance  is  rendered  hard  by  being  impregnated 
with  mineral  salts. 

On  sawing  up  a  bone  it  will  be  seen  that  it  is  in  some  parts 
dense  and  close  in  texture,  appearing  like  ivory,  whilst  in 
others  it  is  open  and  spongy,  and  we  distinguish  two  forms  of 
bony  tissue,  the  dense  or  compact,  and  the  spongy  or  cancel- 
lated. On  closer  examination,  however,  it  will  be  seen  that 
the  bony  matter  is  everywhere  porous,  and  that  the  difference 
between  the  two  varieties  of  tissue  arises  from  the  fact  that  the 
compact  tissue  has  fewer  spaces  and  more  solid  matter  between 
them,  arid  that  the  cancellated  has  larger  cavities  and  more 
slender  intervening  bony  partitions.  In  all  bones  the  compact 
tissue,  being  the  stronger,  lies  on  the  surface  of  the  bone,  and 
forms  an  outer  shell  or  crust,  whilst  the  lighter  spongy  tissue 
is  contained  within.  The  shafts  of  the  long  bones  are  almost 
entirely  made  up  of  the  compact  substance,  except  that  they 
are  hollowed  out  to  form  a  central  canal  —  the  medullary  canal 
—  for  the  reception  of  the  marrow.  Marrow  is  also  found  in 
the  spongy  portions  of  the  bone  in  the  spaces  between  the  bony 
partitions. 

The  hard  substance  of   all  bone   is   arranged  in  bundles  of 


CHAP.  III.] 


BONE. 


21 


bony  fibres  or  lamella,  which  in  the  cancellated  texture  join 
and  meet  together  so  as  to  form  a  structure  resembling  lattice- 
work (cancelli),  and  whence  this  tissue  receives  its  name.  In 
the  compact  tissue  these  lamellse  are  usually  arranged  in  close 
rings  around  canals  which  carry  blood-vessels  in  a  longitu- 
dinal direction  through  the  bones.  Between  the  lamellge  are 
branched  cells  which  lie  in  cell-spaces  or  cavities  called  lacunce, 
and  running  out  in  a 
wheel  -  like  or  radial 
direction  from  each  la- 
cuna are  numerous  tiny 
canals  or  canaliculi 
connecting  one  cell- 
space  or  lacuna  with 
another,  and  forming  a 
system  of  minute  inter- 
communicating chan- 
nels. 

All  bones  are  cov- 
ered by  a  vascular 
fibrous  membrane,  the 
periosteum,  and,  unlike 
cartilage,  the  bones  are 
plentifully  supplied 
with  blood.  If  we 
strip  this  periosteum 
from  a  fresh  bone, 
we  see  many  bleeding  ^  14._TEANSvEESR  SKCT.ON  OF  COMPACT 

points  representing  the     TISSUE  (OF  HUMERUS).    (Magnified  about  loOdiam- 

points     at     which     the     eterS-}     (ShaW->.    Three  of  the  Ha versian  canals 
r  are  seen,  with  their  concentric  rings  faintly  indi- 

blood- vessels  penetrate     cated ;  also  the  lacunae,  with  the  canaliculi  extend- 


ing from  them  across  the  direction  of  the  encircling 
lamellae,  or  concentric  rings. 


the  bone.  After  en- 
tering the  bone  the 
blood  runs  through  longitudinal  channels  which  communicate 
freely  with  one  another,  and  are  called,  from  the  name  of 
their  discoverer,  Htiversian  canals.  Around  these  Haversian 
canals,  as  we  have  already  stated,  the  lamellse  are  disposed  in 
rings,  while  the  lacunae  containing  the  bone-cells  are  also 
arranged,  between  the  lamellse,  in  circles  around  the  canals. 
As  the  canaliculi  run  in  a  radial  direction  from  the  lacunse,  it 


22  ANATOMY   FOK   NUKSES.  [CHAP.  Ill 

follows  that  the  innermost  ones  must  run  into  the  Haversian 
canals,  so  that  there  is  a  direct  communication  between  the 
blood  in  these  canals  and  the  cells  in  the  lacunae.  In  this  way 
the  whole  substance  of  the  bone  is  penetrated  by  intercom- 
municating channels,  and  nutrient  matters  and  mineral  salts 
from  the  blood  in  the  Haversian  canals  can  find  their  way  to 
every  part. 

The  mineral  or  earthy  substance  which  is  deposited  in  bone, 
and  which  makes  it  hard,  amounts  to  about  two-thirds  of  the 
weight  of  the  bone.  It  consists  chiefly  of  phosphate  of  lime, 
with  about  a  fifth  part  of  carbonate  of  lime,  and  a  small  portion 
of  other  salts.  The  soft  or  animal  matter  consists  chiefly  of 
blood-vessels  and  connective  tissue,  and  may  be  resolved  by  boil- 
ing almost  entirely  into  gelatine  :  it  constitutes  about  one-third 
of  the  weight  of  the  bone.  This  proportion  of  animal  and  earthy 
constituents  is,  however,  subject  to  variations.  In  children  the 
animal  matter  is  apt  to  predominate,  and  we  find  that  their 
bones  are  more  liable  to  be  bent  when  injured,  or  only  partially 
broken,  as  in  the  typical  "green-stick"  fracture.  Again,  in  aged 
people  the  earthy  constituents  increase,  the  animal  matter  be- 
comes deficient  in  quality  and  quantity,  and  consequently  their 
bones  are  brittle,  and  more  liable  to  fracture. 

In  the  re-union  of  fractured  bones  new  bony  tissue  is  formed 
between  and  around  the  broken  ends,  connecting  them  firmly 
together;  and  when  a  portion  of  bone  dies,  a  growth  of  new 
bone  very  generally  takes  place  to  a  greater  or  less  extent,  and 
the  dead  part  is  thrown  off.  The  periosteum  is  largely  con- 
cerned in  this  process  of  repair ;  for  if  a  portion  of  the  perios- 
teum be  stripped  off,  the  subjacent  bone  will  be  liable  to  die, 
while  if  a  large  part  or  the  whole  of  a  bone  be  removed,  and 
the  periosteum  at  the  same  time  left  intact,  the  bone  will 
wholly,  or  in  a  great  measure,  be  regenerated. 

In  the  embryo  the  foundation  of  the  skeleton  is  laid  in  cartilage,  or  in  primi- 
tive membranous  connective  tissue,  ossification  of  the  bones  occurring  later. 
The  hardening  or  ossification  of  the  bones  is  accomplished  by  the  penetration  of 
blood-vessels  and  bone-cells,  called  osteo-blasts,  rfrom  the  periosteum.  As 
they  penetrate  into  the  cartilaginous  or  membranous  models,  they  absorb  the 
cartilage  and  connective  tissue  and  deposit  the  true  bone  tissue  at  various 
points  until  they  form  the  particular  bony  structure  with  which  we  are  familiar. 


CHAPTER  IV. 

THE   SKELETON. 

THE  bones  are  the  principal  organs  of  support,  and  the  pas- 
sive instruments  of  locomotion.  Connected  together  in  the 
skeleton,  they  form  a  framework  of  hard  material,  affording 
attachment  to  the  soft  parts,  maintaining  them  in  their  due 
position,  sheltering  such  as  are  of  delicate  structure,  giving  sta- 
bility to  the  whole  fabric,  and  preserving  its  shape. 

The  entire  skeleton  in  the  adult  consists  of  two  hundred  dis- 
tinct bones.  These  are  :  — 

The  spine,  or  vertebral  column  (sacrum  and  coccyx 

included) 26 

Cranium 8 

Face 14 

Os  hyoides,  sternum,  and  ribs 26 

Upper  extremities 64 

Lower  extremities 62 

200 

In  this  enumeration  the  patellce,  or  knee-pans,  are  included  as 
separate  bones,  but  the  smaller  sesamoid  bones,  and  the  small 
bones  of  the  ear,  are  not  included. 

These  bones  may  be  divided,  according  to  their  shape,  into 
four  classes  :  Long,  Short,  Flat,  and  Irregular. 

The  long  and  short  bones  are  found  in  the  extremities.  The 
flat  and  irregular  bones  are  found  in  the  trunk  and  head,  with 
the  exception  of  the  patellse,  which  are  two  small  flat  bones 
found  in  the  lower  extremities,  and  the  scapula,  which  are  also 
two  flat  bones  usually  reckoned  among  the  bones  of  the  upper 
extremities. 

The  bones  of  the  trunk  and  head  are  used  chiefly  to  form 

23 


24 


ANATOMY  FOE   NURSES. 


[CHAP.  IV. 


FIG.  15.— THE  SKELETON,  a,  parietal 
bone;  6,  frontal;  c,  cervical  vertebrae;  d, 
sternum ;  e,  lumbar  vertebrae ;  /,  ulna  ;  g,  ra- 
dius; ft,  wrist  or  carpal  hours;  i,  metacarpal 

bones;  k,  phalanges;  /,  tibia:  in,  fibula;  n, 
tarsal  bones;  o,  metacarpal;  p,  phalanges; 
q,  patella;  r,  femur;  s,  haunch-bone;  t, 
burner  us ;  u,  clavicle. 


cavities  and  to  support  and 
protect  the  organs  contained 
in  these  cavities.  The  bones 
of  the  extremities  enclose  no 
cavities,  and  are  chiefly  used 
in  the  upper  extremity  for 
tact  and  prehension,  and  in 
the  lower  for  support  and 
locomotion ;  in  both  situa- 
tions they  form  a  system  of 
levers.  If  the  surface  of  any 
bone  is  examined,  certain 
eminences  and  depressions 
are  seen,  which  are  of  two 
kinds :  articular  and  non- 
articular.  Non-articular  pro- 
cesses and  depressions  serve 
for  attachment  of  ligaments 
and  muscles ;  the  articular 
are  provided  for  the  mutual 
connection  of  joints. 

Long  bones.  —  A  long  bone 
consists  of  a  lengthened 
cylinder  or  shaft  and  two 
extremities.  The  shaft  is 
formed  mainly  of  compact 
tissue,  this  compact  tissue 
being  thickest  in  the  mid- 
dle ;  it  is  hollowed  out  in 
the  interior  to  form  the 
medullary  canal.  The  ex- 
tremities are  made  up  of 
spongy  tissue  with  only  a 
thin  coating  of  compact  sub- 
stance, and  are  more  or  less 
expanded  for  greater  con- 
venience of  mutual  connec- 
tion, and  to  afford  a  broad 
surface  for  muscular  attach- 
ment. All  long  bones  are 


CHAP.  IV.] 


THE   SKELETON. 


25 


FIG.  10.  —  THE  CLAVICLE. 


more  or  less  curved,  which  confers  upon  them  a  certain  amount 
of  elasticity,  and  gives  them  a  more  graceful  outline. 
Long  bones  of  upper  extremity :  — 

Clavicle  (collar  bone) 2 

Humerus  (arm) 2 

Ulna'2     I  (forearm)  4 

Radius,  2  j  v 

Metacarpus  (palm  of  the  hand) 10 

Phalanges  (fingers) .'    .     .    28 

46 

The  clavicle  forms  the  anterior  portion  of  the  shoulder.     It 
articulates  by  its  inner  extremity  with  the  sternum,  and  by  its 

outer  extrem- 
ity with  the 
acromion  pro- 
cess l  of  the 
scapula.  In 

the  female,  the  clavicle  is  generally  less  curved, 
smoother,  and  more  slender  than  in  the  male.  In 
those  persons  who  perform  considerable  manual 
labour,  which  brings  into  constant  action  the 
muscles  connected  with  this  bone,  it  acquires 
considerable  bulk. 

The  humerus  is  the  longest  and  largest  bone 
of  the  upper  limb.  The  upper  extremity  of  the 
bone  consists  of  a  rounded  head  joined  to  the 
shaft  by  a  constricted  neck,  and  of  two  eminences 
called  the  greater  and  lesser  tuberosities.  The  rounded  head ;  gt, 
head  articulates  with  the  glenoid  cavity  of  the  ^at«r  ^™£_ 
scapula.  The  constricted  neck  above  the  tuber-  berosity;6,groove 
osities  is  called  the  anatomical  neck,  and  that 
below  the  tuberosities,  the  surgical  neck,  from 
its  being  often  the  seat  of  fracture.  The  lower  extremity  of  the 

1  All  eminences  and  projections  of  bones  are  termed  processes,  and  these 
processes  were  named  by  the  early  anatomists,  either  from  their  shape  or  use, 
or  from  their  fancied  resemblance  to  some  well-known  object.  It  is  well  to  look 
up  the  meaning  of  these  Greek  or  Latin  words  which  are  used  so  plentifully  in 
naming  all  parts  of  the  skeleton  ;  the  whole  subject  will  become  more  interest- 
ing, more  readily  understood,  and  more  easily  remembered. 


FIG.  17.  — THE 
HUMERUS.      a, 


26 


ANATOMY   FOK   NQKSES. 


[CHAP.  IV. 


bone  is  flattened  from  before  backwards  into  a  broad  articular 
surface,  which  is  divided  by  a  slight  ridge  into  two  parts,  by 
means  of  which  it  articulates  with  the  ulna 
and  radius. 

The  ulna  (elbow  bone)  is  placed  at  the 
inner  side  of  the  forearm,  parallel  with  the 
radius.      Its   upper  extremity  presents   for 
examination  two  large  curved  processes  and 
two   concave    cavities;    the   larger   process 
forms  the  head  of  the  elbow,  and  is  called 
the  olecranon  process.    The  lower  extremity 
of  the  ulna  is  of  small  size,  and  is  excluded 
from  the  wrist  by  a  piece  of  fibro-cartilage. 
The  radius  is  situated  on  the  outer  side 
of   the  forearm.     The  upper  end  is  small 
and  rounded  with  a  shallow  depression  on 
FIG.  is.  —  THE  ULNA  its  upper  surface  for  articulation  with  the 
AND  RADIUS,    i,  radms;   hunierus    an(J  a  prominent  ridge  about  it, 

2,    ulna;    o,    olecranon    ..,.,'.         ,       »  .,  ;,  -      ,  .    , 

process,  on  the  anterior  like  the  head  oi  a  nail,  by  means  ot  winch 
surf  ace  of  which  are  seen  it  rotates  within  the  lesser  sigmoid  cavity 

» 


the    large    (gs)   and  the 

small    (Is)   cavities,    for    of    the    ulna. 


The 


of  the  head  of  the  radius,    dius     is     large,    and 
radiuf^5  A>  ^^     f    formS  the  Chief  Part 

of  the  wrist. 

Each  metacarpus  is  formed  by  five 
bones.  These  metacarpal  bones  are 
curved  longitudinally,  so  as  to  be  con- 
vex behind,  concave  in  front  ;  they  ar- 
ticulate by  their  bases  with  the  bones  of 
the  wrist  and  with  one  another,  and  the 
heads  of  the  bones  articulate  with  the 
phalanges. 

The  phalanges,  or  digits,  are  the  bones       FTG-  10.-  BUNKS 

_      .  WRIST  AND  HAND. 

of  the  lingers;  they  are  fourteen  in  metaearpal  bones  ;  pi,  p«,  J>«, 
number  (in  each  hand),  three  for  each  phalanges;  3,  bones  of  the 

wrist. 

finger,  and   two  for  the   thumb.      The 

first  row  articulates  with  the  metacarpal  bones  and  the  second 
row  of  phalanges  ;  the  second  row,  with  the  first  and  third  ;  and 
the  third,  with  the  second  row. 


CHAP.  IV.] 


THE    SKELETON. 


27 


Long  bones  of  the  lower  extremity  :  — 

Femur  (thigh  bone)  ...........       2 

*>  ............  * 


Metatarsus  (sole  and  instep  of  foot)    .....     10 
Phalanges  (toes)  ............     28 

44 

The  bones  of  the  lower  extremity  correspond  to  those  of  the 
upper  extremity,  and  bear  a  rough  resemblance  to  them. 

The  femur  is  the  longest,  largest,  and  strongest  bone  in  the 
skeleton.  In  the  erect  position  it  is  not  vertical,  being  sepa- 
rated from  its  fellow  above  by  a  considerable  in- 
terval, which  corresponds  to  the  entire  breadth 
of  the  pelvis,  but  inclining  gradually  down- 
wards and  inwards,  so  as  to  approach  its  fellow 
towards  its  lower  part,  for  the  purpose  of  bring- 
ing  the  knee-joint  near  the  line  of  gravity  of 
the  body.  The  degree  of  inclination  varies  in 
different  persons,  and  is  greater  in  the  female 
than  the  male,  on  account  of  the  greater  breadth 
of  the  pelvis.  The  upper  extremity  of  the 
femur,  like  that  of  the  humerus,  consists  of  a 
rounded  head  joined  to  the  shaft  by  a  constricted 
neck,  and  of  two  eminences,  called  the  greater 
and  lesser  trochanters.  The  head  articulates 
with  the  cavity  in  the  os  innominatum,  called 
the  acetabulum.  The  lower  extremity  of  the. 
femur  is  larger  than  the  upper,  is  flattened  from 
before  backwards,  and  divided  into  two  large 
eminences  or  condyles  by  an  intervening  notch. 
It  articulates  with  the  tibia  and  the  patella,  or 
knee-pan.  FIG.  20.  —  THE 

The  tibia  is  situated  at  the  front  and  inner  FEMUR   grounded 

head;    gtr,   «jivntrr 

side  of  the   leg,  and  forms  what   is  popularly  trochanter;^,  leas- 
known  as  the  shin  bone.     In  the  male,  its  direc-  er  trimmer;    n, 

11GC1C. 

tion  is  vertical  and  parallel  with  the  bone  of  the 
opposite  side  ;  but  in  the  female  it  has  a  slight  oblique  direction 
outwards,  to  compensate  for  the  oblique  direction  of  the  femur 
inwards.     The  upper  extremity  is  large,  and  expanded  into  two 


28 


ANATOMY   FOR   NUKSEiS. 


[CHAP.  IV. 


lateral  eminences  with  concave  surfaces  which  receive  the  con- 
dyles  of  the  femur.  The  lower  extremity  is  much  smaller  than 
the  upper;  it  is  prolonged  downwards  on  its 
inner  side  into  a  strong  process,  the  internal 
malleolus.  It  articulates  with  the  fibula  and 
one  of  the  bones  of  the  ankle. 

The  fibula  is  situated  at  the  outer  side  of  the 
leg.  It  is  the  smaller  of  the  two  bones,  and,  in 
proportion  to  its  length,  the  most  slender  of  all 
the  long  bones :  it  is  placed  nearly  parallel  with 
the  tibia.  The  upper  extremity  consists  of  an 
irregular  rounded  head  by 
means  of  which  it  articu- 
lates with  the  tibia.  The 
lower  extremity  is  pro- 
longed downwards  into  a 
pointed  process,  the  external 
malleolus,  which  lies  iust 

K,,*    im,  J 

FIG.  21.— BONES  beneath  the  skin.     It  artic- 
OF  THE  RIGHT  LEG.  ulates  with  the  tibia  and  one 

o,  tibia;  /,  fibula;       »  .,       -,  e  .-,  n  *, 

etu  and  itu,  lateral  of  the  bones  of  the  ankle, 
eminences  for  re-       The  metatarsus  is  formed 

ception      of      con-    .        _        ,  ,_. 

dyies  of  femur;  h,  by  five  bones.      Ihese  meta- 
head  of  fibula;  im,  tarsal  bones  closely  resemble 

internal  malleolus;  ,    ' 

em,  external  maiie-  the  metacarpal  bones  of  the 
olus-  hand.    Each  bone  articulates 

with  the  tarsal  bones  by  one  extremity,  and 
by  the  other  with  the  first  row  of  phalanges. 

The  phalanges  of  the  foot,  both  in  number       FIG.  22.  — BONES  OF 

,  ,  .        THE  ANKLE  AND  FOOT. 

and  general  arrangement,  resemble  those  in    m\  to  m5,  metatarsai 

the  hand,  there  being  two  in  the  great  toe    bones  5    h>  pi™i""-<-s; 
,  co,  os    calcis,   or   heel 

and  three  in  each  of  the  other  toes. 
Short  bones :  — 

Scaphoid. 

Semilunar. 

Cuneiform* 

Pisiform. 
Trapezium. 
Tnipczoid. 
Os  magnum. 
Unciform. 


Bones  of 
"  the  carpus 
or  wrist. 


bone. 


Os  ealcis. 

Astragalus. 

Cuboid. 

Scaphoid. 

Internal  cuneiform. 

Middle  cuneiform. 

External  cuneiform.  J 


Bones  of 
the  tarsus 
or  ankle. 


CHAP.  IV.]  THE   SKELETON.  29 

The  bones  forming  the  wrists  and  ankles  are  small  pieces  of 
bone  irregularly  shaped,  and  united  together  by  ligaments 
(vide  Figs.  19  and  22).  Their  texture  is  spongy  throughout, 
excepting  at  their  surface,  where  there  is  a  thin  crust  of  com- 
pact substance :  they  are  closely  welded  together,  and  yet,  by 
the  arrangement  of  their  ligaments,  allow  of  a  certain  amount 
of  motion.  There  are  eight  carpal  or  wrist  bones  and  seven 
tarsal  or  ankle  bones.  The  carpal  bones  are  arranged  in  two 
rows,  upper  and  lower,  between  the  bones  of  the  forearm  and 
metacarpal  bones.  They  are  named,  from  their  shape,  scaphoid, 
semilunar,  cuneiform,  etc.  The  tarsal  bones  are  larger  and 
more  irregularly  shaped  than  the  carpal.  The  largest  and 
strongest  of  these  is  the  heel  bone  (os  calcis),  which  serves  to 
transmit  the  weight  of  the  body  to  the  ground,  and  forms  a 
strong  lever  for  the  muscles  of  the  calf  of  the  leg. 


FIG.  23.  — OCCIPITAL  BONE.    Inner  surface.    9,  9  and  10,  10,  depressions  for  recep- 
tion of  lobes  of  brain;  11,  foramen  magnum. 

Flat  bones.  —  We  find  the  bony  tissue  expands  into  broad  or 
elongated  flat  plates  where  the  principal  requirement  is  either 
extensive  protection  or  the  provision  of  the  broad  surfaces  for 


30 


ANATOMY   FOR   NUKSES. 


[CHAP.  IV. 


muscular  attachment.  The  flat  bones  are  composed  of  two  thin 
layers  of  compact  tissue,  inclosing  between  them  a  variable 
quantity  of  cancellous  tissue.  In  the  bones  of  the  skull  this 
outer  layer  is  thick  and  tough  ;  the  inner  one  thinner,  denser, 
and  more  brittle.  The  cancellated  tissue  lying  between  the 
two  layers,  or  "tables  of  the  skull,"  is  called  the  diploe. 
Flat  bones  of  the  head  :  — 

Occipital     .............     1 

Parietal  ............     .     .     2 

Frontal   ..............    JL 

4 

The  occipital  bone  is  situated  at  the  back  and  base  of  the 
skull.  At  birth  the  bone  consists  of  four  parts,  which  do  not 
unite  into  a  single-bone  until  about  the  sixth  year.  The  internal 
surface  is  deeply  concave,  and  presents  many  eminences  and  de- 

pressions for  the 
reception  of  parts 
of  the  brain. 
There  is  a  large 
hole  —  the  fora- 
men magnum  - 
in  the  more  in- 
terior portion  of 
the  bone,  for  the 
transmission  of 
the  medulla  ob- 
longata,  the  en- 
larged portion  of 
the  spinal  cord. 

The-    parietal 
bones    (paries,   a 
wall)     form      by 
their    union    the 
FIG.  24.  —  PARIETAL  BONE.    Inner  surface.    A,  parietal  de-    sjcles   a,^  roof   of 
)>i<->sion;  E,  furrow  for  ramification  of  arteries. 

the    skull.      The 

external  surface  is  convex  and  smooth  ;  the  internal  surface  is 
concave,  and  presents  eminences  and  depressions  for  lodging 
the  convolutions  of  the  brain  and  numerous  furrows  for  the 
ramifications  of  arteries. 


CHAP.  IV.] 


THE   SKELETON. 


31 


The  frontal  bone  resembles  a  cockle  shell  in  form.  It  not 
only  forms  the  forehead,  but  also  enters  into  the  formation  of 
the  roof  of  the  orbits,  and  of  the  nasal  cavity.  The  arch  formed 


FIG.  25.  —  FRONTAL  BONE.    Outer  surface.    1,  frontal  eminence;  7,  roof  of  orbital 
cavity ;  10,  orbital  arch. 

by  part  of  the  frontal  bone  over  the  eye  is  sharp  and  prominent 
and  affords  that  organ  considerable  protection  from  injury.  At 
birth  the  bone  consists  of  two  pieces,  which  afterwards  become 
united,  along  the  middle  line,  by  a  suture  which  runs  from  the 
vertex  of  the  bone  to  the  root  of  the  nose.  This  suture  usually 
becomes  obliterated  within  a  few  years  after  birth,  but  it  occa- 
sionally remains  throughout  life. 
Flat  bones  of  the  face :  — 

Nasal 2 

Lachrymal -2 

Vomer 1 

5 

The  two  nasal  bones  are  two  small  oblong 
bones,  varying  in  size  and  form  in  different  in- 
dividuals ;  they  are  placed  side  by 
side  at  the  middle  and  upper  part 
of  the  face,  forming  by  their  junc- 
tion "the  bridge  "  of  the  nose. 
FIG.  26. -NA-  The  lachrymal  are  the  smallest 

SAL  BONE.    Outer 

surface.  A, inter-  and  most  fragile  bones  or  the  lace.  FIG.-JT.— LAC  n- 
nai  border;  B,  They  are  situated  at  the  front  part  KYMAI.  Boir«. 
external  border.  J  .  Outer  surface. 

of  the  inner  wall  or  the  orbit,  and 
resemble  somewhat  in  form,  thinness,  and  size,  a  finger-nail. 


32 


ANATOMY  FOR  NURSES. 


[CHAP.  IV. 


FIG.  28.  —  VOMER.    Side  view. 


The  vomer  is  a  single  bone 
placed  at  the  back  part  of  the 
nasal  cavity,  and  forms  part  of 
the  septum  of  the  nose.  It  is 
thin,  and  shaped  somewhat  like 
a  plough-share,  but  varies  in 
different  individuals,  being  frequently  bent  to  one  or  the  other 
side. 

Flat  bones  of  the  trunk :  — 

Scapula,  shoulder-blade 2 

Os  innominatum,  haunch-bone 2 

Sternum,  breast-bone 1 

Ribs 24 

Patella _2 

31 

The    scapula,    or 
shoulder-blade,  is  a 
large  flat  bone,  tri- 
angular  in    shape, 
placed  between  the 
first  and  eighth  ribs 
on  the  back  part  of  the 
thorax,  where  it  affords 
considerable  protection  to 
the  lungs.      It  is   unevenly 
divided  by  a  very  prominent 
ridge,  the  spine  of  the  scapula, 
which  terminates  in  a  large  trian- 
gular projection   called,  from  the 
Greek,  acromion  process,  or  summit 
of   the    shoulder.       Below   the  acro- 
mion process,  and  at  the  head  of  the 
shoulder-blade,  is   a  shallow  socket, 
the   glenoid    cavity,   which   receives 
the  head  of  the  humerus. 

The  sternum,  or   breast-bone,  is  a 
flat    narrow    bone,    situated    in    the 

median  line  in  the  front  of  the  chest,    ,  FIG  29.- SCAPULA    inner  sur- 

face.    7,  glenoid  cavity ;  9,  end  of 

and  consisting,  in  the  adult,  of  three    spine;  10,  acromion  process. 


CHAP.  IV.] 


THE    SKELETON. 


33 


FIG.  30.  — STERNUM.     Front   and    side 
view. 


portions.  It  has  been  likened  to  an  ancient  sword.  The  upper 
piece,  representing  the  handle, 
is  termed  the  manubrium  or 
handle ;  the  middle  and  largest 
piece,  which  represents  the  chief 
part  of  the  blade,  is  termed  the 
gladiolus  ;  and  the  inferior  piece, 
which  is  likened  to  the  point  of 
the  sword,  is  termed  the  ensiform 
appendix.  On  both  sides  of  the 
upper  and  middle  pieces  are 
notches  for  the  reception  of  the 
sternal  ends  of  the  ribs.  The 
ensiform  appendix  is  cartilagi- 
nous in  structure  in  early  life, 
but  is  more  or  less  ossified  at 
the  upper  part  in  the  adult:  it 
has  no  ribs  attached  to  it.  The 
sternum  is  about  six  inches  long, 
being  rather  longer  in  the  male 
than  in  the  female. 

The  ribs  are  elastic  arches  of  bone,  forming  the  chief  part 
of  the  thoracic  walls  (vide  Fig.  47).  They  are  usually  twelve 
in  number  on  each  side.  They  are  all  connected  behind  with 
the  vertebrae  of  the  spine,  and  the  first  seven  pairs  are  con- 
nected with  the  sternum  in  front  through  the  intervention  of 
the  costal  cartilages  :  these  first  seven  pairs  are  called  from  their 
attachment  the  vertebro-sternal,  or  true  ribs.  The  remaining 
five  pairs  are  termed  false  ribs ;  of  these,  the  first  three,  being 
attached  in  front  to  the  costal  cartilages,  are  usually  called  the 
vertebro-costal,  while  the  two  remaining,  being  unattached  in 
front,  are  termed  vertebral,  or  floating  ribs.  The  convexity  of 
each  curved  rib  is  turned  outwards  so  as  to  give  roundness  to 
the  sides  of  the  chest  and  increase  the  size  of  its  cavity ;  each 
slopes  downwards  from  its  vertebral  attachment,  so  that  its 
sternal  end  is  considerably  lower  than  its  dorsal.  The  spaces 
left  between  the  ribs  are  called  the  intercostal  spaces. 

The  os  innominatum,  or  nameless  bone,  so  called  from  bearing 
no  resemblance  to  any  known  object,  is  a  large  irregular-shaped 
bone,  which,  with  its  fellow  of  the  opposite  side,  forms  the  sides 


34 


ANATOMY   FOE,   NURSES. 


[CHAP.  IV. 


and  front  wall  of  the  pelvic  cavity.  In  young  subjects  it  con- 
sists of  three  separate  parts,  and  although  in  the  adult  these 
have  become  united,  it  is  usual  to  describe  the  bone  as  divisible 
into  three  portions, — the  ilium,  the  ischium,  and  the  pubes.  The 


H 


FIG.  31.— O8  INNOMINATUM.  Outer  surface.  R,  0,  crest  of  ilium,  just  below  0 
is  seen  the  upper  anterior  spinous  process ;  J,  tuberosity  of  ischium ;  T,  part  of 
pubes,  between  J  and  T  is  seen  the  thyroid  foramen ;  H,  acetabulum,  below  //  is 
seen  end  of  pubic  bone  which,  with  its  fellow  of  opposite  side,  forms  the  symphysis 
pubis.  (For  further  illustration,  vide  Figs.  45  and  4(5.) 

ilium,  so  called  from  its  supporting  the  flank,  is  the  upper  broad 
and  expanded  portion  which  forms  the  prominence  of  the  hip. 
The  ischium  is  the  lower  and  strongest  portion  of  the  bone, 
while  the  pubes  is  that  portion  which  forms  the  front  of  the 
pelvis.  Where  these  three  portions  of  the  bone  meet  and  finally 
ankylose  is  a  deep  socket,  called  the  acetabulum,  into  which  the 
head  of  the  femur  fits.  Other  points  of  special  interest  to  note 
in  the  ossa  innominata  are  (1)  the  spinous  processes  formed  by 


CHAP.  IV.]  THE   SKELETON.  35 

the  projections  of  the  crest  of  the  ilium  in  front,  above  and 
below,  the  two  upper  or  superior  spinous  processes  being  in  par- 
ticular well  known  and  convenient  landmarks  used  by  surgeons 
in  making  anatomical  measurements ;  (2)  the  largest  foramen 
in  the  skeleton,  known  as  the  door-like  or  thyroid  foramen,  sit- 
uated between  the  ischium  and  pubes ;  and  (3)  the  symphysis 
pubis,  or  pubic  articulation,  which  also  serves  for  a  convenient 
landmark  in  making  measurements. 

The  patella,  or  knee-cap,  is  a  small,  flat,  triangular  bone,  placed 
in  front  of  the  knee-joint.  It  is  generally  regarded  as  analogous 
to  the  olecranon  process  of  the  ulna,  which  also  occasionally 
exists  as  a  separate  piece  of  bone.  The  knee-cap  serves  to  pro- 
tect the  front  of  the  knee-joint. 

Irregular  bones.  —  The  irregular  bones  are  those  which,  on 
account  of  their  peculiar  shape,  cannot  be  grouped  under  either 
of  the  preceding  heads. 

Irregular  bones  of  the  head  :  — 

Temporal 2 

Sphenoid 1 

Ethmoid 1 

4 

The  temporal  bones  are  situated  at  the  sides  and  base  of  the 
skull.  They  are  named  temporal  from  the  Latin  word,  tempus, 
time,  as  it  is  on  the  temple  the 
hair  first  becomes  gray  and  thin, 
and  thus  shows  the  ravages  of 
time.  The  temporal  bones  are 
divided  into  three  parts :  the 
hard,  dense  portion,  called  pe- 
trous ;  a  thin  and  expanded 
scale-like  portion,  called  squa- 
mous  ;  and  a  mastoid  portion, 
which  is  perforated  by  numerous 
holes  and  contains  a  number  of  FlG  32. —  TEMPORAL  BONE.  Outer 

Cells.      The   internal  ear,  the  es-    surface.     1,   squamous  portion  ;    7,  ex- 
, .    ,  .  , ,  £  ,  ternal    opening    of    auditory    canal    m 

sentiai  part  ot  the  organ  01  near-  petrous  portion ;  8,  mastoid  portion ;  3, 

ing,   is    Contained    in    a   Series   of    glenoid  cavity  for  reception  of  condyle 
.,     _  .      .        of  lower  jaw. 

cavities,  channelled  out  of  the 

substance  of  the  petrous  portion.     Between  the  squamous  and 


36 


ANATOMY   FOE,   NURSES. 


[CHAP.  IV, 


petrous  portions  is  a 
socket  for  the  recep- 
tion of  the  condyle  of 
the  lower  jaw. 

The  sphenoid  bone 
(sphen,  a  wedge)  is 
situated  at  the  ante- 
rior part  of  the  base 

FIG.  33.  —  SPHENOID  BONE.    Anterior  surface.    6,    of   the  skull,   articulat- 
greater  wing ;  17,  lesser  wing. 


cranial  bones,  which  it  binds  firmly  and  solidly  together 
form  it  somewhat  resembles  a  bat  with 
extended  wings. 

The  ethmoid  bone  is  an  exceedingly 
light,  spongy  bone,  placed  between  the 
two  orbits  and  at  the  root  of  the  nose, 
contributing  to  form  a  part  of  each  of 
these  cavities.  The  portion  of  the 
bone  situated  at  the  back  of  the  nose, 
and  closing  the  skull  cavity  in  front, 
is  pierced  by  numerous  holes,  through 
which  the  nerves,  conveying  the  sense 
of  smell,  pass.  Descending  from  this 
perforated  plate,  on  either  side  of  the 
nasal  cavity,  are  two  masses  of  very 
thin,  spongy,  bony  tissue. 

The  irregular  bones  of  the  face  :  — 


In 


FIG.  34.  —  ETHMOID  BONE. 
Posterior  surface.  2,  cribri- 
form, or  perforated  plate. 


Malar 2 

Palate 2 

Inferior  turbinated 2 

Superior  maxillary 2 

Inferior  maxillary 1 

9 


The  malar  or  cheek  bones  form  the  prominence  of  the  cheek, 
and  part  of  the  outer  wall  and  floor  of  the  orbit. 

The  palate  bones  form  (1)  the  back  part  of  the  roof  of  the 
mouth  ;  (2)  part  of  the  floor  and  outer  wall  of  the  nose ;  and 
(3)  a  very  small  portion  of  the  floor  of  the  orbit. 


CHAP.  IV.] 


THE  SKELETON. 


37 


The  inferior  turbinated  bones  are  situated  on  the  outer  wall 
of  each  side  of  the  nostril.     Each  consists  of  a  layer  of  thin, 


FIG.  35.  —  MALAR  BONE.    Outer  surface.     FIG.  36.  —  PALATE  BONE.    Inner  surface. 

spongy  bone,  curled  upon  itself  like  a  scroll ;  hence  its  name, 
"  turbinated." 

The  superior  maxillary  is  one  of  the  most  important  bones 
of  the  face,  in  a  surgical  point  of 
view,  on  account  of  the  number  of 
diseases  to  which  some  of  its  parts 
are  liable.  With  its  fellow  of  the 
opposite  side,  it  forms  the  whole  of 
the  upper  jaw.  Each  bone  assists 
in  forming  part  of  the  floor  of  the 

orbit,  the  floor  and  outer  wall  of  the  nose,  and  the  greater  part 
of  the  roof  of  the  mouth.     That  part  of  the  bone  which  con- 
Outer  Surface. 


FIG.  37.  —  INFERIOR  TURBINATED 
BONE.    Convex  surface 


focww 


FIG.  38.  —  SUPERIOR  MAXILLARY  BONK.    Outer  surface. 


38 


ANATOMY  FOK  NUKSES. 


[CHAP.  IV. 


Ceroneid  process. 


QmdyU. 


for  facM  artery. 


-AngU. 


tains  the  teeth  is  called  the  alveolar  process,  and  is  excavated 
into  cavities,  varying  in  depth  and  size  according  to  the  size  of 
the  teeth  they  contain.  There  are  eight  cavities  in  each  bone : 
those  for  the  canine  teeth  are  the  deepest ;  those  for  the  molars 
are  widest  and  subdivided  into  minor  cavities;  those  for  the 
incisors  are  single,  but  deep  and  narrow. 

The   inferior   maxillary,   or    lower    jaw,   is   the   largest   and 
strongest  bone  of  the  face,  and  serves  for 
the  reception  of  the  lower  teeth.     At  birth, 
it  consists  of  two  lateral  halves,  which  join 
and  form  one  bone  during  the  first  or  sec- 
ond year.     The  lower  jaw  undergoes  sev- 
eral changes  in  shape   during  life,  owing 
mainly  to  the  first 
and    second    denti- 
tion, to  the  loss  of 
teeth  in  the  aged, 
and  the  subsequent 
absorption   of   that 
part    of    the    bone 
which       contained 

them.  It  articulates,  by  its  condyles,  with  the  sockets  in  the 
temporal  bones. 

The  hyoid,  os  hyoides,  or  tongue  bone,  is  an  isolated,  U-shaped 
bone  lying  in  front  of  the  throat,  just 
above  "  Adam's  apple  "  ;  it  supports  the 
tongue,  and  gives  attachment  to  some  of 
its  numerous  muscles. 

The  irregular  bones  of  the  trunk  are 
comprised  in  the  spine,  which  is  formed 
of  a  series  of  bones  called  vertebrae. 
The  vertebrae  are  thirty-three  in  num- 
ber, and  according  to  the  position  they 
occupy  are  named :  — 

Cervical 7 

Dorsal .     12 

Lumbar 5 

Sacral 5 

Coccygeal 4 

33 


FIG.  39.  —  INFERIOR  MAXILLARY  BONE.    Outer  surface. 


FIG.  40.  — HYOID  BONE. 


CHAP.  IV.] 


THE   SKELETON. 


39 


The  vertebrse  in  the  upper  three  portions  of  the  spine  are 
separate  throughout  the  whole  of  life ;  but  those  found  in  the 
sacral  and  coccygeal  regions  are,  in  the  adult,  firmly  united,  so 
as  to  form  two  bones,  five  entering  into  the  upper  bone  or 
sacrum,  and  four  into  the  terminal  bone  of  the  spine,  or  coccyx. 

Each  vertebra  consists  of  two  essential  parts,  an  anterior 
solid  portion  or  body,  and  a  posterior  portion  or  arch.  The 
bodies  of  the  vertebrse 
are  piled  one  upon 
another,  forming  a 
solid,  strong  pillar, 
for  the  support  of  the 
cranium  and  trunk, 
the  arches  forming  a 
hollow  cylinder  be- 
hind for  the  protec- 
tion of  the  spinal 
cord.  Each  arch  has 
seven  processes:  four 

articular,    two     trans-  FIG.  41.  — A  CERVICAL  VERTEBRA.    Inferior  sur- 

Verse      and     One     SDi-  ^ace-    *>  spinous  process,  slightly  bifid ;  4,  transverse 

**  process ;  5,  articular  process,  inferior  surface.    Below 

nOUS     process.         The  the  arch,  or  hollow  portion,  is  seen  the  solid  portion, 

different  vertebrae  are    or  body- 

connected  together  by  means  of  the  articular  processes,  and  by 
disks  of  intervertebral  nbro-eartilage  placed  between  the  ver- 
tebral bodies,  while  the  transverse  and  spinous  processes  serve 
for  the  attachment  of  muscles  which  move  the  different  parts  of 
the  spine.  In  the  cervical  region  of  the  vertebral  column  the 
bodies  of  the  vertebrse  are  smaller  than  in  the  dorsal,  but  the 
arches, are  larger;  the  spinous  processes  are  short,  and  are  often 
cleft  in  two,  or  bifid.  The  first  and  second  cervical  vertebrae 
differ  considerably  from  the  rest.  The  first,  or  atlas,  so  named 
from  supporting  the  head,  has  practically  no  body,  and  may  be 
described  as  a  bony  ring  divided  into  two  sections  by  a  trans- 
verse ligament.  The  dorsal  section  of  this  ring  contains  the 
spinal  cord,  and  the  ventral  or  front  section  contains  the  bony 
projection  which  arises  from  the  front  of  the  second  cervical  ver- 
tebra, or  axis.  This  bony  projection,  or  odontoid  process,  is 
really  the  body  of  the  atlas,  which  in  early  life  separates  from  its 
own  vertebra  and  grows  on  the  axis.  Around  this  peg  the  atlas 


40 


ANATOMY   FOR  NURSES. 


[ClIAP.   IV. 


A— 


rotates  when  the  head  is  turned  from  side  to  side,  carrying  the 

skull,  to  which  it  is  firmly  articulated, 
with  it.  The  bodies  of  the  dorsal  ver- 
tebrae are  larger  and  stronger  than 
those  of  the  cervical;  they  contain 
depressions  for  the  reception  of  the 
vertebral  ends  of  the  ribs.  The  bodies 
of  the  lumbar  vertebrae  are  the  largest 
and  heaviest  in  the  whole  spine.  The 
sacrum,  formed  by  the  union  of  the 
five  sacral  vertebrae,  is  a  large  trian- 
gular bone  situated  like  a  wedge 
between  the  ossa  innominata ;  it  is 
curved  upon  itself  in  such  a  way  as 
to  give  increased  capacity  to  the  pel- 
vic cavity  (vide  Fig.  46).  The  coccyx 
(cuckoo's  bill)  is  usually  formed  of 
four  small  segments  of  bone,  and  is 
the  most  rudimentary  part  of  the 
vertebral  column. 

The  vertebral  column  as  a  whole.  — 
The  spinal  column  in  a  man  of  aver- 
age height  is  about  twenty-eight 
inches  long.  Viewed  from  the  side 
it  presents  four  curvatures ;  one,  with 
the  convexity  forwards  in  the  cervi- 
cal region,  is  followed  in  the  dorsal, 
by  a  curve  with  its  concavity  towards 
the  chest.  In  the  lumbar  region  the 
curve  has  again  its  convexity  for- 
wards, while  in  the  sacral  and  coccy- 
geal  regions  the  concavity  is  turned 
inwards.  These  curvatures  confer  a 
considerable  amount  of  springiness 
FIG.  42. -SIDE  VIEW  OF  SPI-  upon  t^e  gpinal  column  wnich  would 

NAL  COLUMN,  WITHOUT  SACRUM       L 

AND  COCCYX,    i  to  7,  Cervical  be  lacking  were  it  a  straight  column  : 

vertebn,;  s  t«  in  dorsal  verte-  th    elasticity  is  further  increased  by 

brae  ;  20  to  24,  lumbar  vertebrae ;  J 

A,  A,  spin.. us  processes;  c,  D,  the  disks  of  fibro-cartilage  lying  be- 
axis.  the  vertebrae.      These   disks  or  pads 


CHAP.  IV.] 


THE   SKELETON. 


41 


also  mitigate  the  effects  of  concussion  arising  from  falls  or 
blows,  and  allow  of  a  certain  amount  of  motion  between 
the  vertebrae.  The  amount  of  motion  permitted  is  greatest 
in  the  cervical  region.  Between  each  pair  of  vertebrae  are 
apertures  through  which  the  spinal  nerves  pass  from  the  spinal 
cord. 

The  skull  as  a  whole.  —  The  skull,  formed  by  the  union  of  the 
cranial  and  facial  bones  already  described,  is  divisible  into  cra- 
nium or  brain  case,  and  the  anterior  region  or  face. 


FIG.  43.  —THE  SKULL,    a,  nasal  bone ;  6,  superior  maxillary ;  c,  inferior  maxillary ; 
d,  occipital ;  e,  temporal ;  /,  parietal ;  g,  frontal  bone. 

The  bones  of  the  cranium  begin  to  develop  at  a  very  early 
period  of  foetal  life,  owing  to  the  importance  of  the  organ  they 
have  to  protect.  Before  birth  the  bones  at  the  top  and  sides  of 
the  skull  are  separated  from  each  other  by  membranous  tissue 
in  which  bone  is  not  yet  formed.  The  spaces  occupied  by  this 
membranous  tissue  are  termed  the  fontanelles,  so  named  from 
the  pulsations  of  the  brain,  which  can  be  seen  in  some  of  them, 


42  ANATOMY  FOR  NURSES.  [CHAP.  IV. 

rising  like  the  water  in  a  fountain.  There  are  six  of  these 
fontanelles.  The  anterior  fontanelle  is  the  largest,  and  is  a 
lozenge-shaped  space  between  the  angles  of  the  two  parietal 
and  two  frontal  bones.  The  posterior 
fontanelle  is  much  smaller  in  size,  and 
is  a  triangular  space  between  the  occip- 
ital and  two  parietal  bones.  The  other 
(A  four  fontanelles,  two  on  each  side  of 
the  skull,  are  placed  at  the  inferior 
angles  of  the  parietal  bones  :  they  are 
unimportant.  T]^e  posterior  fontanelle 
is  closed  by  an  extension  of  the  ossify- 
ing process  a  few  months  after  birth. 

FIG.  44.— THE  SKULL  AT    ,-.,  .  .  ,.,     ,, 

BIRTH.  Superior  surface,  i,  The  anterior  remains  open  until  the 
posterior  fontanelle;  2,  sagit-  second  year,  and  occasionally  persists 

tel    suture ;    4,  anterior    f  on-  i        ,    -i  •  /•          mi       i  •   ,  i         in 

taneiie;  A,  A,  bi-parietai  throughout  lite.  I  he  base  of  the  skull 
diameter;  B,  B,  bi-temporai  js  mucn  thicker  and  stronger  than  the 

walls  and  roof ;  it  presents  a  number 

of  openings  for  the  passage  of  the  cranial  nerves,  blood-ves- 
sels, etc. 

The  diameters  of  the  foetal  skull  given  by  King  are :  — 

Occipito-mental  (from  posterior  fontanelle  to  chin)  .  .  5-|-  inches. 
Occipito-frontal  (centre  of  frontal  bone  to  occiput)  .  .  4|-  inches. 
Bi-parietal  (from  one  parietal  prominence  to  another)  .  3^-  inches. 

The  fcetal  cranial  bones  being  imperfectly  ossified,  and  their 
edges  separated  by  membranous  intervals,  they  are  readily 
moulded,  and  they  overlap  one  another  more  or  less  during 
parturition. 

The  pelvic  cavity.  —  The  pelvis,  so  called  from  its  resemblance 
to  a  basin,  is  stronger  and  more  massively  constructed  than 
either  the  cranial  or  the  thoracic  cavity.  It  is  composed  of 
four  bones,  the  ossa  innominata  forming  sides  and  front,  and 
the  sacrum  and  coccyx,  completing  it  behind.  It  is  divided 
by  a  brim  or  prominent  line,  the  linea  ilio-pectinea,  into  the 
false  and  true  pelvis.  The  false  pelvis  is  all  that  expanded 
portion  of  the  pelvis  situated  above  the  brim :  it  forms  an  in- 
complete or  "  false  "  basin.  The  true  pelvis  is  all  that  portion 
situated  below  the  brim.  Its  cavity  is  a  little  wider  in  every 


CHAP.  IV.]  THE   SKELETON.  43 

direction  than  the  brim  itself,  while  the  false  pelvis  is  a  great 


FIG.  45. —  MALE  PELVIS. 

deal  wider.     The  brim  is,  therefore,  a  somewhat  narrower  bony 


FIG.  46.  —  FEMALE  PELVIS. 


44 


ANATOMY   FOR   NURSES. 


[CHAP.  IV. 


ring  or  aperture  between  these  two ;  hence  it  is  often  termed 
the  "strait."      The  bony  pelvis  is  a  basin  without  a  bottom. 


J.UESg&RD. 


FIG.  47.  —  THORAX.  1  to  12,  ribs ;  d,  d,  costal  cartilages;  e,  upper  end  of  sternum; 
6,  middle  portion  of  sternum ;  la,  first  dorsal  vertebra ;  12a,  twelfth  dorsal  verte- 
bra; 7a,  seventh  cervical  vertebra;  1  to  7,  true  ribs;  8  to  12,  false  ribs;  11, 12,  float- 
ing ribs. 

The  opening  where  the  bottom  ought  to  be  is  the  inferior  strait 
or  outlet.  The  female  pelvis  differs  from  that  of  the  male  in 
those  particulars  which  render  it  better  adapted  to  parturition, 
notably  in  being  altogether  wider  in  every  direction,  which 
gives  more  room  for  the  child  to  pass ;  in  being  altogether  shal- 


CHAP.  IV.] 


THE   SKELETON. 


45 


lower,  which  lessens  the  distance  through  which  the  child  has 
to  be  propelled;  and  lastly,  in  the  bones  being  thinner  and 
smoother. 

The  diameters  of  an  average  female  pelvis  given  by  King 
are :  — 

Antero-posterior  diameter  of  brim  or  inlet ....  4  inches. 

Transverse  diameter  of  brim  or  inlet 4  inches. 

Oblique  diameter  of  brim  or  inlet 4J  to  5  inches. 

Antero-posterior  of  outlet 4J  to  5  inches. 

Transverse  of  outlet 4  inches. 

Oblique  of  outlet 4  inches. 

The  thoracic  cavity.  —  The  thorax  or  chest  is  an  elongated, 
conical-shaped  cage,  formed  by  the  sternum  and  costal  cartilages 
in  front,  the  twelve  ribs  on  each  side,  and  the  bodies  of  the 
twelve  dorsal  vertebrse  behind.  It  contains  and  protects  the 
principal  organs  of  respiration  and  circulation. 


TABLE   OF  THE  BONES. 


HEAD. 


Cranium. 

Face. 

Occipital. 

Nasal. 

Parietal. 

Lachrymal. 

Temporal. 

Malar. 

Frontal. 

Superior  maxillary,    i 

Ethmoid. 

Inferior  maxillary.    • 

Sphenoid. 

Palate. 

Inferior  turbinated. 

Vomer.       / 

Os  hyoides. 

7  cervical. 
12  dorsal. 
Vertebrse  -     5  lumbar. 

5  sacral,  or  sacrum. 

4  coccygeal.  or  coccyx. 
Ribs. 
Sternum. 
Ossa  innominata. 


TRUNK. 


46 


ANATOMY   FOR  NURSES. 


[CHAP.  IV. 


Clavicle. 

Humerus. 

Ulna. 

Radius. 

Metatarsus. 

Scaphoid. 

Semi  lunar. 

Cuneiform. 

Pisiform. 

Trapezium. 

Trapezoid. 

Os  magnum. 

Unciform. 
Phalanges  or  digits. 


Carpus 


Femur. 
Tibia. 
Fibula. 
Metatarsus. 

Os  calcis. 

Astragalus. 

Cuboid. 
Tarsus  \  Scaphoid. 

Internal  cuneiform. 

Middle  cuneiform. 

External  cuneiform. 
Phalanges  or  digits. 


CHAPTER  V. 

JOINTS. 

THE  various  bones  of  which  the  skeleton  consists  are  con- 
nected together  at  different  parts  of  their  surfaces,  and  such 
connections  are  called  joints  or  articulations. 

In  all  instances  some  softer  substance  is  placed  between  the 
bones,  uniting  them  together,  or  clothing  the  opposed  surfaces  ; 
but  the  manner  in  which  the  several  pieces 
of  the  skeleton  are  thus  connected  varies 
to  a  great  degree.  We  distinguish  three 
varieties ;  viz.  those  which  are  (1)  immov- 
able, (2)  slightly  movable,  (3)  freely 
movable. 

The  immovable  articulations.  —  The  bones 
of  the  cranium  and  the  facial  bones  (with 
the  exception  of  the  lower  jaw)  have 
their  adjacent  surfaces  applied  in  close 

contact,  with  only  a  thin  layer  of  fibrous  tissue  or  of  cartilage 
placed  between  their  margins.     In  most  of  the  cranial  bones 

this  union  occurs  by  means  of  toothed 
edges  which   fit   into  one  another  and 
form  jagged  lines   of   union  known  as 
sutures.     The  suture  between  the  fron- 
tal  and  parietal   bones    is   called    the 
coronal   suture;    between   the   parietal 
FIG.49.-AMIXEDARTICU-  and  occipital,  the  lambdoidal;  and  be- 
LATION.  a,  6,  disk  of  fibro-car-  tween  the  two  parietal  bones,  along  the 

tilage;   c,  articular  cartilage;         .^      j.         Qn    the    t         Qf    the    crown, 
a,  bone. 

the  sagittal  suture. 

The  slightly  movable  or  mixed  articulation.  —  In  this  form  of 
articulation  the  bony  surfaces  are  usually  joined  together  by 

47 


48 


ANATOMY  FOR   NURSES. 


[CHAP.  V. 


broad,  flattened  disks  of  fibre-cartilage,  as  in  the  articulations 
between  the  bodies  of  the  vertebrae.  These  intervertebral 
disks  being  compressible  and  extensile,  the  spine  can  be  moved 
to  a  limited  extent  in  every  direction.  In  the  pelvis  the  articu- 
lation between  the  two  pubic  bones  (symphysis  pubis),  and 
between  the  sacrum  and  ilia  (sacro-iliac  articulation),  are  also 
slightly  movable.  The  pubic  bones  are  united  by  a  disk  of 
fibro-cartilage  and  by  ligaments.  In  the  sacro-iliac  articulation 
the  sacrum  is  united  more  closely  to  the  ilia,  the  articular  sur- 
faces being  covered  by  cartilage  and  held  together  by  ligaments. 
The  movable  articulations.  —  This  division  includes  the  com- 
plete joints,  —  joints  having  a  secreting  membrane  placed  be- 
tween their  opposing  surfaces,  which  keeps  them  well  lubricated 
and  capable  of  free  movement  one  upon  the  other.  Each  articular 
end  of  the  bone  is  covered  by  cartilage,  which  provides  surfaces 
A  of  remarkable  smoothness,  and 

these  surfaces  are  lubricated  by 
the  synovial  fluid  secreted  from 
the  delicate  synovial  membrane 
which  lines  the  cavity  of  the 
joint.  This  membrane  is  contin- 
uous with  the  margin  of  the  ar- 
ticular cartilage,  and  along  with 
them  completely  encloses  the 
joint  cavity.  The  bones  are 
united  by  fibrous  connective 
tissue  in  the  various  forms  of 
ligaments,  such  as  membranous 

capsules,  flat  bands,  or  rounded  cords.  These  ligaments  are  not 
always  so  tight  as  to  maintain  the  bones  in  close  contact  in  all 
positions  of  the  joint,  but  are  rather  tightened  in  some  positions 
and  relaxed  in  others,  so  that  in  many  cases  they  are  to  be  looked 
upon  chiefly  as  controllers  of  movements,  and  not  as  serving 
solely  to  hold  the  bones  together.  The  bones  are  likewise  held 
together  in  these  joints  by  atmospheric  pressure  and  by  the 
surrounding  muscles. 

The  varieties  of  joints  in  this  class  have  been  determined 
by  the  kind  of  motion  permitted  in  each.  They  are  as 
follows  :  — 

(1)    Gliding  joint.     The   articular  surfaces  are    nearly  flat, 


SVNOVIAL.  FOUD 


JOINT-CAVITY 


FIG.  50.  —  A  SIMPLE  COMPLETE  JOINT. 
The  synovial  membrane  is  represented 
by  dotted  lines. 


CHAP.  V.]  JOINTS.  49 

and  admit  of  only  a  limited  amount  of  gliding  movement, 
as  in  most  of  the  articulations  of  the  wrist  and  ankle,  and  in  the 
joints  between  the  articular  processes  of  the  vertebrae. 

(2)  Hinge  joint.     The  articular  surfaces  are  of  such  shape 
as  to  permit  of  movement,  to  and  fro,  in  one  plane  only,  like  a 

'door  on  its  hinges.  These  movements  are  called  flexion  and 
extension,  and  may  be  seen  in  the  articulation  of  the  arm  with 
the  forearm,  in  the  ankle  joint,  and  in  the  articulations  of  the 
phalanges. 

(3)  Ball  and  socket  joint.     In  this  form  of  joint   a  more  or 
less  rounded  head  is  received  into  a  cup-like  cavity,  as  the  head 
of  the  femur  into  the  acetabulum,  and  the  head  of  the  humerus 
into  the  glenoid  cavity  of  the  scapula.     Movement  can  take 
place  freely  in  any  direction,  but  the  shallower  the  cup,  the 
greater  the  extent  of  motion. 

(4)  Pivot  joints.     In   this   form,  one   bone   rotates    around 
another  which  remains  stationary,  as  in  the  articulation  of  the 
atlas  with  the  axis,  and  in  the  articulation  of  the  ulna  and 
radius.     In  the  articulation  of    the  ulna  and  radius,  the  ulna 
remains   stationary  and   the  radius   rotates   freely  around   its 
upper  end.     The  hand  is  joined  to  the  lower  end  of  the  radius, 
and  the  radius,  in  rotating,  carries  the  hand  with  it;  thus,  the 
palm  of  the  hand  is   alternately  turned  upwards  and  down- 
wards.    When  the  palm  is   turned   upwards,  the   attitude    is 
called  supination  ;  when  downwards,  pronation. 

The  different  kinds  of  movement  of  which  bones  thus  con- 
nected are  capable  are,  —  flexion  and  extension  ;  abduction  and 
adduction  ;  rotation  and  circumduction. 

A  limb  is  flexed,  when  it  is  bent;  extended,  when  it  is 
straightened  out.  It  is  abducted,  when  it  is  drawn  away  from 
the  middle  line ;  adducted,  when  it  is  brought  to  the  middle 
line.  It  is  rotated,  when  it  is  made  to  turn  on  its  own  axis; 
circumducted,  when  it  is  made  to  describe  a  conical  surface,  by 
rotation  around  an  imaginary  axis.  No  part  of  the  body  is 
capable  of  perfect  rotation,  as  a  wheel,  for  the  simple  reason  that 
sucli  motion  would  necessarily  tear  asunder  all  the  vessels, 
nerves,  muscles,  etc.,  which  unite  it  with  other  parts. 

As  the  synovial  membranes  are  intimately  connected  with 
the  joints,  it  may  be  well  to  give  a  brief  description  of 
them  here. 


50  ANATOMY  FOR   NURSES.  [CHAP.  V. 

The  synovial  membranes  are  composed  entirely  of  connective 
tissue,  with  the  usual  cells  and  fibres  of  that  tissue.  They  are 
distinguished  by  the  nature  of  their  secretion,  which  is  a  viscid, 
glairy  fluid,  resembling  the  white  of  an  egg  and  named  synovia. 
From  its  nature,  it  is  well  adapted  for  diminishing  friction,  and 
thereby  facilitating  motion. 

These  membranes  are  found  surrounding  and  lubricating  the 
cavities  of  the  movable  joints  in  which  the  opposed  surfaces 
glide  on  each  other ;  in  these  situations  they  are  called  articular 
synovial  membranes.  They  are  found  forming  sheaths  for  the 
tendons  of  some  of  the  joints,  and  thus  facilitating  their  motion 
as  they  glide  in  the  fibrous  sheaths  which  bind  them  down 
against  the  bones;  they  are  here  called  vaginal  synovial  mem- 
branes, or  synovial  sheaths.  Lastly,  they  are  found  in  the  form 
of  simple  sacs,  interposed,  so  as  to  prevent  friction,  between  two 
surfaces  which  move  upon  each  other,  and  in  these  situations 
they  take  the  name  of  bursal  synovial  membranes,  or  synovial 
bursse.  These  bursso  may  be  either  deep  seated  or  subcu- 
taneous. The  former  are,  for  the  most  part,  placed  between  a 
muscle  and  a  bone,  or  between  a  tendon  and  a  bone.  The  sub- 
cutaneous burs86  lie  immediately  under  the  skin,  and  occur  in 
various  parts  of  the  body,  interposed  between  the  skin  and 
some  firm  prominence  beneath  it.  The  large  bursa  situated 
over  the  patella  is  a  well-known  example  of  this  class,  but 
similar,  though  smaller,  bursee  are  found  also  over  the  olecranon, 
the  malleoli,  the  knuckles,  and  other  prominent  parts. 

TABLE  OF  JOINTS. 

1.  Synchondrosis.  —  A  thin  layer  of  cartilage  is  inter- 
posed  between   the  bones  to  which   it   adheres 

closely  on  each  side. 
SYNARTHROSIS, 

2.  Suture.  —  A  thin  layer  of  fibrous  tissue  is  inter- 

OR.  *s 

T  posed  between  the  bones.     Sutures  may  be  den- 

IMMOVABLE  JOINT. 

tated,  tooth-like;   serrated,  saw-like;    squamous, 

scale-like ;    harmonic,  smooth ;    and  grooved,  for 
the  reception  of  thin  plates  of  bone. 

1.   Symphysis.  —  The  bones  are  united  by  a  plate  or 
disk  of  fibro-cartilage  of  considerable  thickness; 


AMPHIARTHROSIS, 


OR 


or  by  articular  cartilages  lined  by  a  partial  syno- 
vial membrane. 

SLIGHTLY  MOVABLE    0     .,      .          .        ,_,  ,  .,    ,  , 

2.    Syndesmons.  —  1  he  bony  surfaces  are  united  by 

an   intrrosscoiis   ligament,  as  in  the  lower  tibio- 
fibular  articulation. 


CHAP.  V.] 


JOINTS. 


DlARTHROSIS, 
OR 

MOVABLE  JOINT. 


1.  Arthrodia.  —  Gliding  joint;   articulates  by  plane 
surfaces  which  glide  upon  each  other. 

2.  Ginglymus.  —  Hinge  joint;  moves  backwards  and 
forwards  in  one  plane. 

3.  Enarthrosis.  —  Ball  and  socket  joint;   articulates 
by  a  globular  head  in  a  cup-like  cavity. 

4.  Diartlirosis    rotataria.  —  Articulates    by    a    pivot 
process  turning  within  a  ring,  or  by  a  ring  turn- 
ing round  a  pivot. 


CHAPTER  VI. 


MUSCULAR  TISSUE :  STRIATED  OR  STRIPED  ;  NON-STRIATED  OR 
PLAIN;  ATTACHMENT  OF  MUSCLES  TO  SKELETON;  PROMI- 
NENT MUSCLES  OF  HEAD  AND  TRUNK ;  PROMINENT  MUSCLES 
OF  LIMBS. 

MUSCULAR  tissue  is  the  tissue  by  means  of  which  the  active 
movements  of  the  body  are  produced.  It  is  a  higher  kind  of 
tissue  than  the  connective,  which,  as  we  have  seen,  is  used 
chiefly  for  mechanical  purposes.  Muscular  tissue  is  irritable, 
and  if  we  irritate  or  stimulate  it,  it  will  respond.  We  may  irri- 
tate or  stimulate  the  bones,  ligaments, 
or  other  connective  tissue  structures 
and  they  will  not  respond,  they  will 
remain  immovable ;  if,  however,  we 
stimulate  muscular  tissue,  it  will  show 
its  response  to  the  stimulation  by 
contracting.  This  power  of  the 
muscle  to  contract  is  called  muscular 
contractility.  All  muscular  tissue 
consists  of  fibres,  and  whenever  a 
muscle  fibre  contracts,  it  tends  to 
bring  its  two  ends,  with  whatever  may 
be  attached  to  them,  together.  Influ- 
ences which  irritate  or  stimulate 
muscle  fibres  are  spoken  of  under 
the  general  name  of  stimuli. 

Muscle  fibres  are  of  two  different 
kinds,  and  we  therefore  distinguish 
two  varieties  of  muscular  tissue,  the  striped  or  striated,  and  the 
plain  or  non-striated.  The  striated  muscle  is  nearly  always 
under  the  control  of  the  will,  and  is  often  spoken  of  as  voluntary 

62 


FIG.  51.  —  MUSCULAR  FIBRE. 
Highly  magnified.  (E.  A.  S.) 
The  nuclei  are  seen  on  the  flat  at 
the  surface  of  the  fibre,  and  in 
profile  at  the  edges:  the  sar- 
coleuiina  is  not  seen. 


CHAP.  VI.] 


THE   MUSCLES. 


53 


muscle ;  the  non-striated  is  usually  withdrawn  from  the  control 
of  the  will,  and  is  often  termed  involuntary  muscle. 

Voluntary,  striated  muscle  is  composed  of  long  slender  fibres 
measuring  on  an  average  about  -%$-$  inch  in  diameter,  but  hav- 
ing a  length  of  an  inch  or  more.  Each  fibre  consists  of  three  dis- 
tinct elements :  (1)  contractile  substance,  forming  the  centre  and 
making  up  most  of  the  bulk  of  the  fibre ;  (2)  nuclei,  which  lie 
scattered  upon  the  surface  of  the  contractile  substance ;  (3)  the 
sarcolemma,  a  thin,  structureless  tube,  which  tightly  encloses 
the  contractile  substance  and  the  nuclei. 

If  we  examine  a  fresh  muscle  fibre  microscopically,  we  see 
that  the  contractile  substance  is  marked  with  very  fine  indistinct 
longitudinal  lines,  or  strise;  and  if  we  treat  the  fibre  with 
certain  chemical  agents, 
we  find  by  slightly  teas- 
ing it  with  a  needle,  or 
some  other  delicate  instru- 
ment, that  it  breaks  up 
along  the  longitudinal 
lines  into  a  number  of  fine 
fibrils  or  fibrillse.  Again, 
if  we  examine  the  fibre 
still  further,  we  find  that 
in  addition  to  the 
tudinal  striation  it 
crossed  by  more 
narrow  dark  and  light 

bands  Or  Stripes,  the  rela-    transverge    cleavage;    «,  ~b,    partially   detached 

tive  width   of  the   Stripes    disks;  &'  detached  disk,  more  highly  magnified, 

•, .  ,1        showing  the  sarcous  elements. 

varying  according  as  the 

fibre  is  seen  in  a  state  of  contraction  or  relaxation.  So  that  if 
now  we  soak  a  fibre  in  an  acid  solution  for  twenty-four  hours, 
and  then  tease  it,  we  find  that  instead  of  breaking  up  longitudi- 
nally into  fibrill^e,  it  breaks  across  into  thin  disks.  We  thus  see 
that  by  breaking  up  in  these  two  directions  we  may  conceive  of 
the  fibre  as  being  resolvable  into  a  multitude  of  tiny  structures, 
which  elementary  structures  have  been  called  sarcous  elements. 
It  is  believed  by  many  observers  that  these  sarcous  elements  are 
definite  aii^  independent  structures,  and  that  they  are  joined 
together  side  by  side,  and  end  to  end,  by  a  peculiar  cementing 


s 


FIG.  52.  —  FRAGMENTS  OF  STRIPED  FIBRES, 
SHOWING  A  CLEAVAGE  IN  OPPOSITE  DIREC- 
TIONS. (Magnified  300  diameters.)  A,  longitu- 
dinal cleavage;  c,  fibrillae  separated  from  one 
another  at  the  broken  end  of  the  fibre;  c' c", 
single  fibrils  more  highly  magnified,  in  c'  the  ele- 
mentary structures  are  square,  in  c"  round;  B, 


54 


ANATOMY   FOK   NURSES. 


[CHAP.  VI. 


R 


substance  ;  this,  however,  is  not  proved,  and  the  ultimate  struct- 
ure of  muscular  fibre  is  still  by  no  means  fully  understood.  This 
much,  however,  is  certain,  that  the  contractile  substance  is  a  com- 
plex chemical  structure,  and  that  the  molecules  of  which  it 
is  composed  readily  change  their  places  under  the  influence  of 
certain  stimuli.  When  a  muscle  contracts,  each  section  or 
sarcous  element  of  the  fibre  broadens  and  shortens.  This 
broadening  and  shortening  is  brought  about  by  the  molecules 

of  each  section  of  the  fibre 
changing  their  places.  We 
shall  have  a  rough  image  of  the 
movements  of  the  molecules 
during  a  muscular  con  traction 
if  we  imagine  a  company  of 
a  hundred  soldiers  ten  ranks 
deep,  with  ten  men  in  each 
rank,  rapidly,  but  by  a  series 
of  gradations,  extending  lat- 
erally into  a  double  line 
with  fifty  men  in  each 
line. 

The  striated  muscles  are 
all  connected  with  nerves, 
and  under  normal  conditions 
do  not  contract  otherwise 
than  by  the  agency  of  the 
nerves.  They  are  also  plenti- 
fully supplied  with  blood- 
vessels. 

The  muscular  fibres  lie 
closely  packed,  their  ends 
lapping  over  on  to  adjacent 

FIG.  53.  -WAVE  OF  CONTRACTION  PASS-  fibres,  and  forming  bundles. 
ING  OVER  A  MUSCULAR  FIBRE  OF  DYTLSCUS. 
Very  highly  ma-nified.    if,  K,  portions  of   Ihese  bundles   are    grouped 

** 


. 

and  in  this  way  the  muscles 
which  are  attached  to  the  skeleton  are  formed. 

Involuntary,  non-striated  muscular  tissue  is  composed  of  long, 
somewhat  flattened,  elongated  fibre-cells.  Each  fibre-cell  con- 
tains an  oval  or  rod-shaped  nucleus,  containing  one  or  more 


CHAP.  VI.]  THE   MUSCLES.  55 

nucleoli.  The  substance  of  the  fibre-cell  is  longitudinally  stri- 
ated, but  does  not  exhibit  transverse  striation.  The  fibre-cells 
lie  side  by  side,  or  lap  over  one  another  at  the  ends,  and  are 
joined  together  by  a  small  amount  of  cement  substance. 

This  kind  of  muscular  tissue  is  found  arranged  around  the 
blood-vessels  and  most  of  the  hollow  viscera.  The  fibres  are 
variously  grouped  in  different  parts  of  the  body ;  sometimes 
crowded  together  in  solid  bundles,  which 
are  arranged  in  layers  and  surrounded  by 
connective  tissue,  as  in  the  intestines ; 
sometimes  arranged  in  narrow  interlacing 
bundles,  as  in  the  bladder;  sometimes  wound 
in  single  or  double  layers  around  the  blood- 
vessels ;  and  again,  running  in  various  direc- 
tions and  associated  with  bands  of  connec- 
tive tissue,  they  form  large  compact  masses, 
as  in  the  uterus. 

Numerous  nerves  are  supplied  to  non- 
striated  muscular  tissue,  and  many  blood- 
vessels. 

The  contraction  of  this  kind  of  muscular 
tissue  is  much  slower  and  lasts  longer  than 
the  contraction  of  the  striated  variety.  As 

i         i      ,1  T  c    ,1          11,  FIG.  54. — FIBRE-CELLS 

a  general  rule  the  muscles  of  the  skeleton  OF  PLAIN  MUSCULAR 
are  thrown  into  contraction  only  by  nervous  TISSUE.  Highly  magni- 
impulses  reaching  them  along  their  nerves ; 
spontaneous  contractions,  as  in  a  case  of  "cramps,"  being  rare 
and  abnormal.  The  plain  muscular  tissue  of  the  internal 
organs,  however,  very  often  contracts  independently  of  the 
central  nervous  system,  and  under  favorable  circumstances  will 
continue  to  do  so  after  the  viscera  have  been  removed  from  the 
body. 

The  great  increase  in  the  muscular  tissue  of  the  uterus  during  gestation 
takes  place  both  by  elongation  and  thickening  of  the  pre-existing  fibre-cells, 
and  also,  it  is  thought,  by  the  development  of  new  fibre-cells  from  .small 
granular  cells  lying  in  the  tissue.  In  the  shrinking  of  the  uterus  after  par- 
turition the  fibre-cells  diminish  to  their  previous  size  ;  many  of  them  become 
filled  with  fat  granules,  and  eventually  many  are,  doubtless,  removed  by 
absorption. 

Development  of  striated  muscular  tissue. —When  the  muscular  fibres 
are  about  to  be  formed,  the  cells  set  apart  for  this  purpose  elongate,  and  their 


56  ANATOMY   FOR   NURSES.  [CHAP.  VI. 

nuclei  multiply,  so  that  each  cell  is  converted  into  a  long,  multi-nucleated 
protoplasmic  fibre.  At  first  the  substance  of  the  fibre  is  not  striated,  but 
presently  it  becomes  longitudinally  striated  along  one  side,  and  about  the 
same  time  a  delicate  membrane,  the  sarcolemma,  may  be  discovered  bound- 
ing the  fibre;  then  transverse  striation  commences,  and  gradually  extends 
around  the  fibre,  and,  finally,  the  nuclei  take  up  their  position  under  the 
sarcolemma. 

Regeneration  of  muscular  tissue.  —  It  was  formerly  thought  that  after 
removal,  by  the  knife,  or  by  disease,  muscular  tissue  was  not  regenerated, 
but  that  any  breach  of  continuity  which  might  occur  in  the  muscle  was  filled 
up  by  a  growth  of  connective  tissue.  It  would  appear,  however,  that  the 
breach  is  after  a  certain  lapse  of  time  bridged  across  by  muscular  substance, 
but  how  the  new  muscular  tissue  is  formed  is  not  fully  understood. 

Attachment  of  muscles  to  the  skeleton.  —  The  muscles  are  sepa- 
rate organs,  each  muscle  having  its  own  sheath  of  connective 
tissue.  The  connective  tissue  extends  also  into  the  muscle,  form- 
ing sheaths  for  the  smaller  bundles,  connecting  and  binding  the 
fibres  and  bundles  together,  and  conducting  and  supporting  the 
blood-vessels  and  nerves  distributed  to  the  muscle  fibres. 

The  muscles  vary  greatly  in  shape  and  size.  In  the  limbs 
they  are  of  considerable  length,  forming  more  or  less  elongated 
straps ;  in  the  trunk  they  are  broad,  flattened,  and  expanded, 
forming  the  walls  of  the  cavities  which  they  enclose. 

They  are  attached  to  the  bones,  cartilages,  ligaments,  and 
skin  in  various  ways,  the  most  common  mode  of  attachment 
being  by  means  of  tendons.  The  muscular  fibres  converge  as 
they  approach  their  tendinous  extremities,  and  gradually  blend 
with  the  fibres  of  the  tendons,  the  tendons  in  their  turn  insert- 
ing their  fibres  into  the  bones.  Sometimes  the  muscles  end  in 
expanded  form  in  the*  flat  fibrous  membranes,  called  aponeuroses. 
Again,  in  some  cases,  the  muscles  are  connected  with  the  bones, 
cartilages,  and  skin,  without  the  intervention  of  tendons  or 
aponeuroses. 

In  the  description  of  muscles  it  is  customary  to  speak  of  the 
attachments  of  their  opposite  ends  under  the  names  of  origin 
and  insertion,  the  first  term  being  usually  applied  to  the 
more  fixed  attachment,  and  the  second  to  the  more  movable 
attachment. 

The  muscular  tissue  or  flesh  forms  a  large  proportion  of  the 
weight  of  the  whole  body.  The  following  has  been  calculated 
for  a  man  of  one  hundred  and  fifty  pounds'  weight  from  the 


p- 


PLATE  I.  —  FORMS  OF  MUSCLES  AND  TENDONS.  A,  adductor  of  thigh ;  B,  biceps  of 
arm;  1),  deltoid;  G,  gastroenemius ;  P',  pronator  of  fore-arm;  P",  pectoral;  A', 
rectus  abdomiuis;  R",  rectus  muscle  of  thigh;  S',  serratus  magnus  of  thorax;  6'", 
semi-membranosus  of  thigh. 


57 


58 


ANATOMY   FOE,   NURSES. 


[CHAP.  VI. 


tables  of  Liebig:  skeleton,  twenty-eight  pounds;  muscles,  sixty- 
two  pounds ;  viscera  (with  skin,  fat,  blood,  etc.),  sixty  pounds. 
The  total  number  of  voluntary  muscles  may  be  stated  at 
three  hundred  and  eleven.  It  is  not  necessary  for  us  to  be  able 
to  distinguish  more  than  a  few  of  the  most  prominent.  We 
may  conveniently  classify  these  into  two  groups :  — 

1.  Chief  muscles  of  the  head  and  trunk. 

2.  Chief  muscles  of  the  limbs. 

Chief   muscles    of   head,    face,   neck,   and    trunk.  —  The   chief 
muscles    of    the   head   are    the    occipital   and   frontal   muscles, 

which,  united  together  by  a  thin 
aponeurosis  extending  over  and 
covering  the  whole  of  the  upper 
part  of  the  cranium,  are  usually 
known  as  one  muscle,  the  occipito- 
frontalis.  The  frontal  portion  of  this 
muscle  is  the  more  powerful ;  by 
its  contraction  the  eyebrows  are  ele- 
vated, the  skin  of  the  forehead 


FIG.  55. — MUSCLES  OF  RIGHT 
EYEBALL  WITHIN  THE  ORBIT. 
Seen  from  the  front.  21,  superior  thrown  into  transverse  wrinkles,  and 

rectus;  22,  inferior  rectus:  23,  ex-     fi       soaln  drawn  forward 
ternal  rectus;  24,  internal  rectus; 
25,  superior  oblique;   26,  inferior 
oblique. 


\ 


There  are  about  thirty  facial  mus- 
cles ;  they  are  chiefly  small,  and  con- 
trol the  movements  of  the  eye,  nose,  and  mouth. 

The  six  muscles  which  move  the  eyeball  are  the  four  straight 
or  recti,  and  the  two  oblique, 
muscles.  The  four  recti  have  a 
common  origin  at  the  bottom 
of  the  orbit ;  they  pass  straight 
forwards  to  their  insertion  into 
the  eyeball,  one,  the  superior 
rectus,  in  the  middle  line  above  ; 
one,  the  inferior  rectus,  oppo- 
site it  below,  and  one  half-way 
on  each  side,  the  external  and 
internal  recti.  The  eyeball  is 

Completely  imbedded  in  fat,  and    from  side-     1!)'  elevator  muscle  of  eyelid; 

22-2(5,  same  as  in  Fig.  55. 

these  muscles  turn  it  as  on  a 

cushion,  the  superior  rectus  inclining  the  axis  of  the  eye  upwards, 


FIG.  56.— MUSCLES  OF  EYEBALL.     Seen 


PLATE  II.  —  MUSCLES  OF  FACE,  HEAD,  AND  NECK.    1,  sterno-cleidomastoid ; 
10,  temporal ;  11,  masseter ;  13,  13,  occipito-f routalis. 


59 


60 


ANATOMY   FOE,   NURSES. 


[CHAP.  VI. 


the  inferior  downwards,  the  external  outwards,  the  internal 
inwards.  The  two  oblique  muscles  are  both  attached  on  the 
outer  side  of  the  ball ;  their  action  is  somewhat  complicated, 
but  their  general  tendency  is  to  roll  the  eyeball  on  its  own 
axis,  and  pull  it  a  little  forward  and  inward. 

The  muscles  of  mastication  are  the  masseter,  the  temporal,  and 
the  external  and  internal  pterygoid.  They  all  have  their  origin 
in  the  immovable  bones  of  the  skull,  and  are  all  inserted  into 
the  movable  lower  jaw.  They  generally  act  in  concert,  bring- 
ing the  lower  teeth  forcibly  into  contact  with  the  upper ;  they 
also  move  the  lower  jaw  forward  upon  the  upper,  and  in  every 
direction  necessary  to  the  process  of  grinding  the  food. 

The  chief  muscles  connecting 
the  tongue  and  tongue  bone  to 
the  lower  jaw  are  the  genio- 
glossus  and  stylo-glossus.  They 
are  interesting  to  us  from  the 
fact  that  during  general  anaes- 
thesia they,  together  with  the 
other  muscles,  become  relaxed, 
and  it  is  necessary  to  press  the 
angle  of  the  lower  jaw  upwards 
and  forwards  in  order  to  pre- 
vent the  tongue  from  falling 
backwards  and  obstructing  the 
larynx. 

The  most  prominent  muscle 
of  the  neck  is  the  sterno-cleido- 
mastoid.  It  is  named  from  its  origin  and  insertion,  arising  from 
part  of  the  sternum  and  clavicle,  and  being  inserted  into  the 
mastoid  portion  of  the  temporal  bone.  This  muscle  is  easily 
recognized  in  thin  persons  by  its  forming  a  cord-like  promi- 
nence obliquely  situated  along  each  side  of  the  neck.  It  serves 
as  a  convenient  landmark  in  locating  the  great  vessels  carrying 
the  blood  to  and  from  the  head.  If  one  of  these  muscles  be 
either  abnormally  contracted  or  paralyzed,  we  get  the  deformity 
called  wry  neck. 

The  muscles  of  the  trunk  may  be  arranged  in  three  groups : 
(1)  muscles  of  the  back ;  (2)  muscles  of  the  thorax ;  (3)  muscles 
of  the  abdomen. 


FIG.  57.  —  MUSCLES  OF  THE  TONGUE. 


PLATE  III.—  MUSCLES  OF  BACK.    50,  latissimus  dorsi ;  51,  trapezius ;  52,  deltoid 

61 


62  ANATOMY   FOli   NUKSES.  [CHAP.  VI. 

The  muscles  of  the  back  are  disposed  in  five  layers,  one  be- 
neath another.  The  two  largest  and  most  superficial  are  the 
trapezius  and  the  latissimus  dorsi. 

The  trapezius  arises  from  the  middle  of  the  occipital  bone, 
and  from  the  spine  as  far  as  the  last  dorsal  vertebra.  From 
this  extended  line  of  origin  the  fibres  converge  to  their  in- 
sertion in  the  acromion  process  and  spine  of  the  scapula. 
The  latissimus  dorsi  arises  from  the  last  six  dorsal  vertebrae, 
and  through  the  medium  of  the  lumbar  aponeurosis,  from  the 
lumbar  and  sacral  part  of  the  spine  and  from  the  crest  of  the 
ilium.  The  fibres  pass  upwards  and  converge  into  a  thick,  nar- 
row band,  which  winds  around  and  finally  terminates  in  a  flat 
tendon,  which  is  inserted  into  the  front  of  the  humerus  just 
below  its  head. 

These  muscles  cover  nearly  the  whole  of  the  back ;  but  as 
they  act  upon  the  bones  of  the  upper  extremity,  they  are  often 
more  properly  reckoned  as  belonging  to  the  muscles  of  that 
region. 

The  muscles  of  the  thorax  are  chiefly  concerned  with  the 
movements  of  the  ribs  during  respiration.  They. are  the  inter- 
costals,  subcostals,  etc. 

The  chief  bulk  of  the  anterior  muscular  wall  of  the  chest  is 
made  up  of  the  pectoral  muscles,  which  arise  mainly  from  the 
front  of  the  sternum.  The  fibres  converging  form  a  thick  mass, 
which  is  inserted  by  a  tendon  of  considerable  breadth  into  the 
upper  part  of  the  humerus.  As  these  muscles  move  the  arm, 
they  are,  like  the  superficial  muscles  of  the  back,  usually  reck- 
oned among  ,the  muscles  of  the  upper  extremity.  Covering  the 
pectoral  muscles  is  a  superficial  fascia  (composed  of  connective 
tissue)  in  which  are  lodged  the  mammary  glands  and  a  variable 
amount  of  fat. 

The  muscular  walls  of  the  abdomen  are  mainly  formed  by 
three  layers  of  muscles,  the  fibres  of  which  run  in  different  direc- 
tions, those'  of  the  superficial  and  middle  layers  being  oblique, 
and  those  of  the  innermost  layer  being  transverse.  In  front, 
these  three  layers  of  muscles  are  replaced  by  tendinous  expan- 
sions or  aponeuroses,  which  meet  in  the  middle  line,  the  line  of 
union  giving  rise  to  a  white  cord-like  line,  the  linea  alba.  On 
each  side  of  this  line  the  fibres  of  a  straight  muscle,  the  rectus 
muscle,  extend  in  a  vertical  direction  between  the  tendinous 


PLATE  IV.  —MUSCLES  OF  CHEST  AND  AKPOMKN.  .",:>,  pectoral  muscle ;  44,  serratus 
magnus ;  34,  external  oblique ;  35,  rectus  alxl. .minis,  the  external  layer  of  aponeurotic 
sheath  is  removed;  38,  linea  alba;  40,  aponeurosis. 

63 


64  ANATOMY   FOR   NURSES.  [CHAP.  VI. 

layers.  The  abdominal  muscles  are  covered  and  lined  by  sheets 
of  fasciae,  some  of  which  are  very  dense  and  strong,  and  serve 
to  strengthen  weak  points  in  the  muscular  walls. 

The  strongest  and  most  superficial  of  the  abdominal  muscles 
is  the  external  oblique,  the  fibres  of  which,  arising  from  the  lower 
eight  ribs,  incline  downwards  and  forwards  and  terminate  in  the 
broad  aponeurosis,  which,  meeting  its  fellow  of  the  opposite  side 
in  the  linea  alba,  covers  the  whole  of  the  front  of  the  abdomen. 
The  lowest  fibres  of  the  aponeurosis  are  gathered  together  in 
the  shape  of  a  thickened  band,  which  extends  from  the  superior 
spinous  process  of  the  ilium  to  the  pubis,  and  forms  the  well- 
known  and  important  landmark,  called  from  the  anatomist  who 
first  described  it,  Poupart's  ligament.  Just  above  this  ligament, 
and  near  the  pubic  bone,  is  an  oblique  opening  which  transmits 
the  spermatic  cord  in  the  male,  or  the  round  ligament  in  the 
female.  This  opening,  called  the  external  abdominal  ring,  is 
often  the  seat  of  hernia. 

The  internal  oblique  muscle  lies  just  beneath  the  external 
oblique.  Its  fibres  run  upwards  and  forwards,  and  end  for  the 
most  part  in  a  broad  aponeurosis.  At  the  outer  border  of  the 
rectus  muscle  this  aponeurosis  divides  into  two  layers,  one  pass- 
ing before,  the  other  behind,  that  muscle :  they  reunite  at  its 
inner  border  in  the  linea  alba,  and  thus  form  a  sheath  for  the 
rectus. 

The  transversalis  muscle  lies  beneath  the  internal  oblique; 
the  greater  part  of  its  fibres  have  a  horizontal  direction,  and 
extend  forward  to  a  broad  aponeurosis  in  front. 

The  rectus  is  a  long,  flat  muscle,  consisting  of  vertical  fibres 
situated  at  the  fore  part  of  the  abdomen,  and  enclosed  in 
the  fibrous  sheath  formed  by  the  aponeuroses  of  the  internal 
oblique.  It  arises  from  the  pubis,  and  is  inserted  into  the  car- 
tilages of  the  fifth,  sixth,  and  seventh  ribs ;  it  is  separated  from 
the  muscle  of  the  other  side  by  a  narrow  interval  which  is  occu- 
pied by  the  linea  alba. 

The  linea  alba,  or  white  line,  is  a  tendinous  band  formed  by 
the  union  of  the  aponeuroses  of  the  two  oblique  and  transverse 
muscles,  the  tendinous  fibres  crossing  one  another  from  side  to 
side.  It  extends  perpendicularly,  in  the  middle  line,  from  the 
ensiform  portion  of  the  sternum  to  the  pubis.  It  is  a  little 
broader  above  than  below,  and  a  little  below  the  middle  it  is 


CHAP.  VI.]  THE   MUSCLES.  65 

widened  into  a  flat  circular  space,  in  the  centre  of  which  is  sit- 
uated the  cicatrix  of  the  umbilicus. 

The  abdominal  muscles  perform  a  threefold  action.  When 
the  pelvis  and  thorax  are  fixed,  they  compress  the  abdominal 
viscera  by  constricting  the  cavity  of  the  abdomen,  in  which 
action  they  are  much  assisted  by  the  descent  of  the  diaphragm. 
By  these  means  the  foetus  is  expelled  from  the  uterus,  the 
faeces  from  the  rectum,  the  urine  from  the  bladder,  and  its  con- 
tents from  the  stomach,  in  vomiting.  If  the  spine  is  fixed, 
these  muscles  raise  the  diaphragm  by  pressing  on  the  abdominal 
viscera,  draw  down  the  ribs,  compress  the  lower  part  of  the 
thorax,  and  assist  in  expiration.  If  the  thorax  is  fixed,  and 
the  trunk  and  arms  raised  and  fixed,  they  draw  the  pelvis 
upwards  as  a  preparatory  step  to  the  elevation  of  the  lower 
limbs  in  the  action  of  climbing. 

The  diaphragm  is  a  thin  musculo-fibrous  partition,  placed 
obliquely  between  the  abdominal  and  thoracic  cavities.  It  is 
fan-shaped,  and  consists  of  muscle  fibres  arising  from  the  whole 
of  the  internal  circumference  of  the  thorax,  and  of  an  aponeu- 
rotic  tendon,  shaped  somewhat  like  a  trefoil  leaf,  into  which 
the  muscle  fibres  are  inserted.  (  Vide  Plate  V.  for  illustration 
of  diaphragm.)  It  has  three  large  openings  for  the  passage 
of  the  aorta,  the  large  artery  of  the  body,  the  inferior  vena 
cava,  the  largest  vein  of  the  body,  and  the  oesophagus  or  gullet ; 
it  has  also  some  smaller  openings,  of  less  importance,  for  the 
passage  of  blood-vessels,  nerves,  etc.  The  upper  or  thoracic 
surface  of  the  diaphragm  is  highly  arched;  the  heart  is  sup- 
ported by  the  central  portion  of  the  arch,  the  right  and  left 
lungs  by  the  lateral  portions,  the  right  side  of  the  arch  being 
slightly  higher  on  the  right  than  on  the  left  side.  The  lower 
or  under  surface  of  the  diaphragm  is  deeply  concave,  and  covers 
the  liver,  stomach,  pancreas,  spleen,  and  kidneys. 

The  action  of  the  diaphragm  modifies  considerably  the  size 
of  the  chest,  and  the  position  of  the  thoracic  and  abdominal 
viscera,  and  it  is  essentially  the  great  respiratory  muscle  of  the 
body.  The  mechanical  act  of  respiration  consists  of  two  sets 
of  movements;  viz.  those  of  inspiration  and  of  expiration,  in 
which  air  is  successively  drawn  into  the  lungs  and  expelled 
from  them  by  the  alternate  increase  and  diminution  of  the 
thoracic  cavity.  The  changes  in  the  capacity  of  the  thorax  are 


66 


ANATOMY   FOR  NURSES. 


[CHAP.  VI, 


effected  by  the  expansion  and  contraction  of  its  lateral  walls, 
called  costal  respiration,  and  by  the  depression  and  elevation 
of  the  floor  of  the  cavity,  through  contraction  and  relaxation 

of  the  diaphragm,  called  dia- 
phragmatic or  abdominal  respi- 
ration. These  two  movements 
are  normally  combined  in  the 
act  of  respiration,  but  in  dif- 
ferent circumstances  one  of 
them  may  be  resorted  to 
more  than  the  other.  Abdom- 
inal respiration  predominates 
in  men  and  in  children,  and 
costal  respiration  in  women. 
In  the  act  of  inspiration  the 
diaphragm  contracts,  and  in 
contracting  flattens  out  and 
descends,  the  abdominal  vis- 
cera are  pressed  downwards, 
and  the  thorax  is  expanded 
vertically.  In  normal  and 
quiet  expiration  the  diminu- 
tion of  the  capacity  of  the 
chest  is  mainly  due  to  the  re- 
turn of  the  walls  of  the  chest 
to  the  condition  of  rest,  in  con- 
sequence of  their  own  elastic 
reaction,  and  of  the  elasticity 
and  weight  of  the  viscera  dis- 
placed by  inspiration.  In  more 
forcible  acts  of  expiration,  and 
in  efforts  of  expulsion  from 
the  thoracic  and  abdominal 
cavities,  all  the  muscles  which 
tend  to  depress  the  ribs,  and 
those  which  compress  the  ab- 
dominal cavity,  concur  in  pow- 
erful action  to  empty  the  lungs,  to  fix  the  trunk,  and  to  expel  the 
contents  of  the  abdominal  viscera.  Thus  the  diaphragm  is  an 
expulsive  as  well  as  the  chief  respiratory  muscle  of  the  body. 


FIG.  58.  —  MUSCLES  OF  ARM.    58,  biceps 

5(J,  triceps. 


CHAP.  VI.] 


THE   MUSCLES. 


67 


Muscles  of  the  upper  extremity. 
—  A  certain  number  of  muscles 
situated  superficially  on  the  trunk 
pass  to  the  bones  of  the  shoulder 
and  of  the  arm,  so  as  to  attach 
the  upper  limbs  to  the  trunk.  Of 
these,  the  two  superficial  muscles 
we  have  mentioned  as  covering 
the  back,  the  trapezius  and  latis- 
simus  dorsi,  and  pectoral  muscles 
covering  the  front  of  the  chest, 
are  the  chief.  The  most  promi- 
nent muscles  found  in  the  upper 
limbs  are :  — 


Deltoid. 

Biceps. 

Triceps. 


Pronators. 
Supinators. 
Flexors. 
Extensors. 


The  deltoid  is  a  coarse  triangu- 
lar muscle  covering  the  top  of 
the  shoulder;  it  extends  down- 
wards and  is  inserted  into  the 
middle  of  the  shaft  of  the  hu- 
merus.  It  raises  the  arm  from  the 
side  so  as  to  bring  it  at  right 
angles  to  the  trunk. 

The  biceps  is  a  long  fusiform 
muscle,  occupying  the  whole  of 
the  anterior  surface  of  the  arm  ; 
it  is  divided  above  into  two 
portions  or  heads,  from  which 
circumstance  it  has  received  its 
name.  It  arises  by  these  two 
heads  from  the  shoulder-joint, 
and  is  inserted  into  the  radius. 

It  flexes  the  forearm  on  the  arm. 

FIG.  59.  —  MUSCLES    IN   FRONT    OF 
ihe  triceps  is  situated  on  the    FOREARM.   6i>,  proimtor  tores  :<;:;.»;:.. 


back  of  the  arm,  extending-  the   (;<i>  (57»  flexors;  70,  supinator  i- 

.  71.  77,  78,  extensors:   </,  annular  nga- 

whole  length  of  the  posterior  sur-   mellt. 


68 


ANATOMY   FOR   NUHSES. 


[CHAP.  VI. 


face  of  the  humerus.  It 
is  of  large  size,  and  divided 
above  into  three  heads ; 
hence  its  name.  It  is 
inserted  into  the  ulna. 
It  is  the  great  extensor 
muscle  of  the  forearm, 
and  is  the  direct  antago- 
nist of  the  biceps. 

The  muscles  covering 
the  forearm  are  disposed 
in  groups,  the  pronators 
and  flexors  being  placed 
on  the  front  and  inner 
part  of  the  forearm,  and 
the  supinators  and  exten- 
sors on  the  outer  side  and 
back  of  the  forearm  :  they 
antagonize  one  another. 
The  pronators  turn  the 
palm  of  the  hand  down- 
wards or  prone,  the  supi- 
nators turn  it  upwards  or 
supine.  The  flexors  and 
extensors  have  long  ten- 
dons, some  of  which  are 
inserted  into  the  bones  of 
the  wrist,  and  some  into 
the  bones  of  the  fingers : 
they  serve  to  flex  and  ex- 
tend the  wrist  and  fingers. 

Muscles  of  the  lower  ex- 
tremity. —  These  include 

FIG.  60.  — MUSCLES  OF  THE  THIGH.     46,  glu-   the  muscles  of  hip,  thigh, 
teus  maximus ;  36,  35,  posterior  femoral;  33,  sar-  ,  ,   ,  T1  . 

torius ;  27,  26,  internal  femoral  or  adductor.  leg>  ancl       ot' 

prominent  of  these  are  : — 


Glutei  or  gluteal  muscles. 
Posterior  femoral. 
Anterior  femoral. 
Internal  femoral. 


Tibialis  anticus. 
Extensors. 
Peroneal. 
Gastrocnemius. 


Soleus. 
Flexors. 
Tibialis  posticus. 


CHAP.  VI.] 


THE   MUSCLES. 


69 


If  we  compare  the  muscles  of  the 
shoulder  and  arm  with  those  of  the 
hip  and  leg,  we  shall  see  that  the  an- 
terior muscles  of  the  former  corre- 
spond roughly  with  the  posterior 
muscles  of  the  latter,  the  muscles  of 
the  hip  and  leg,  however,  being 
larger  and  coarser  in  texture  than 
those  of  the  shoulder  and  arm. 

The  glutei,  or  three  gluteal  mus- 
cles, form  the  chief  prominence  of 
the  buttocks.  They  are  coarse  in 
texture,  and  are  powerful  abductors 
of  the  thigh;  but  the  chief  action 
of  the  largest  of  these  three  muscles, 
the  gluteus  maximus,  is  to  bring  the 
body  into  the  erect  posture  when  the 
trunk  is  bent  forwards  upon  the 
thigh.  It  also  comes  into  operation 
in  ascending  stairs,  in  leaping,  and 
in  rising  from  the  sitting  posture. 

The  posterior  femoral  or  hamstring 
muscles  cover  the  back  of  the  thigh. 
There  are  three  of  these  muscles, 
—  the  biceps,  the  semitendinosus, 
and  the  semimembranosus.  The 
chief  of  these  is  the  biceps,  and  is 
somewhat  analogous  to  the  biceps 
covering  the  front  of  the  arm.  The 
action  of  the  hamstring  muscles  is 
to  flex  the  knee  and  to  extend  the 
hip. 

The  anterior  femoral  muscles  are 
the  quadriceps  and  sartorius.  The 
quadriceps  covers  the  front  of  the 
thigh,  and  is  analogous  to  the  triceps 

covering  the  back  of  the  arm ;   it  is 

•  i  f    ,1        •>  •,        FIG. 61.  —  MuBCLtt OF LBG.  Su- 

the  great  extensor   of   the   leg;    it  PERFICIAL  VJKW  OF  THK  CALF. 

also  flexes  the  hip,  and  antagonizes  22,  temio  Achiiiis:  21,  gastrocne- 

,,  ,.  ,,    ,       ,  ,    .  ,          mius;  18,  soleus;  16,  peroueal  mus- 

the  action  of  the  hamstring  muscles.  cleSt 


70  ANATOMY   FOR   NURSES.  [CHAP.  VI. 

The  sartorius,  or  tailor's  muscle,  is  a  long,  ribbon-like  muscle, 
the  longest  in  the  body:  it  crosses  the  thigh  obliquely  from 
its  origin  in  the  ilium  to  its  insertion  in  the  tibia.  It  is  supposed 
to  be  the  muscle  principally  concerned  in  producing  the  posture 
assumed  by  the  tailor  in  sitting  cross-legged,  and  hence  its  name. 

The  internal  femoral  or  adductor  muscles  occupy  the  internal 
portion  of  the  thigh :  they  are  all  adductors  of  the  thigh. 

The  tibialis  anticus,  the  extensors,  and  the  peroneal  muscles 
cover  the  front  and  outer  side  of  the  leg.  The  gastrocnemius 
and  the  soleus,  the  flexors,  and  the  tibialis  posticus,  cover  the  back 
of  the  leg.  The  action  of  the  tibialis  anticus  and  of  one  of  the 
three  peroneal  muscles  is  to  flex  the  ankle,  while  the  action  of 
the  tibialis  posticus  and  the  other  peroneal  muscles  is  to  extend 
the  ankle.  The  flexors  and  extensors  act  on  the  toes. 

The  gastrocnemius  and  soleus  form  the  calf  of  the  leg;  they 
are  inserted  into  a  common  tendon,  the  tendo  Achillis,  which  is 
the  thickest  and  strongest  tendon  in  the  body,  and  is  inserted 
into  the  os  calcis,  or  heel  bone.  The  muscles  of  the  calf  possess 
considerable  power,  and  are  constantly  called  into  use  in  stand- 
ing, walking,  dancing,  and  leaping ;  hence  the  large  size  they 
usually  present. 

The  sole  of  the  foot  is  protected  by  a  fascia,  called  the  plantar 
fascia,  which  is  very  strong,  and  the  densest  of  all  the  fibrous 
membranes. 

Most  of  the  muscles  are  covered  closely  by  sheets  of  fibrous 
connective  tissue  (fasciae),  and  this  deep  layer  of  tissue  forms  a 
nearly  continuous  covering  beneath  the  superficial  or  subcu- 
taneous layer  of  areolar  connective  tissue,  which  in  a  former 
chapter  we  saw  to  be  continuous  over  the  whole  of  the  body. 
Parts  of  the  deep  fasciae  in  the  vicinity  of  the  larger' joints,  as 
at  the  wrist  and  ankle,  become  blended  into  tight  transverse 
bands  which  serve  to  hold  the  tendons  close  to  the  bones,  and 
receive  the  name  of  annular  ligaments. 


CHAP.  VI.] 


THE   MUSCLES. 


71 


TABLE  OF  tJHIEF  MUSCLES. 
Occipito-frontalis.     HEAD. 

Temporal.  -) 

Masseter.     [  Muscles  of  Mastication. 

Pterygoid.  J 

Exterior  rectus. 

Interior  rectus. 

Superior  rectus. 

Inferior  rectus. 

Superior  oblique. 

Inferior  oblique. 

Genio-glossus.  1 
Stylo-glossus.    J 

Stern  o-cleido-mastoid. 


Muscles  of  the  Eye. 


FACE. 


TONGUE. 

NECK. 


Intercostals. 
Subcostals. 
Levatores  costarum. 
Pectoral  major. 
Pectoral  minor. 


THORAX. 


Diaphragm.     BETWEEN  THORAX  AND  ABDOMEN. 

Obliquus  externus  abdominis.  ~) 

Obliquus  intern  us  abdominis. 

}•  ABDOMEN. 
Transversalis  abdominis. 

Rectus  abdominis. 

Trapezius.  1  „ 

,      .   [BACK. 

Latissimus  dorsi.  J 

Deltoid.     SHOULDER. 

Biceps  flexor  cubiti.         1    . 
Triceps  extensor  cubiti.  J 

Pronators  (2). 

Supinators  (2). 

Flexors  of  the  wrist  (2). 

Flexors  of  fingers  and  thumb  (3) 

Extensors  of  wrist  (3). 

Extensors  of  fingers  and  thumb  (6). 


FOREARM. 


(  Maximus. 
Gluteij  Medius/ 
I  Minimus. 


HIP. 


72 


ANATOMY  FOE  NURSES. 


[CHAP.  VL 


r  Biceps  flexor  cruris. 
Posterior  femoral  J  Semitendinolus. 

I  Semimembranosus. 

Anterior  femoral  {  QuadricePs  exteisor  cruris. 
[  Sartorms. 

{Adductor  longus. 
Adductor  brevis. 
Adductor  magnus. 

Tibialis  anticus. 

Tibialis  posticus. 

Peroneal  (3). 

Gastrocnemius.  !•  LEG. 

Soleus. 

Flexors  of  toes  (4). 

Extensors  of  toes  (4).  > 


THIGH. 


CHAPTER  VII. 

THE   VASCULAR   SYSTEM:    THE  BLOOD. 

HAVING  studied  three  of  the  distinctive  tissues  of  the  body 
(the  epithelial,  connective,  and  muscular),  their  structure,  posi- 
tion in  the  body,  and  the  various  functions  they  are  especially 
adapted  to  perform,  we  shall  next  consider  the  vascular,  respi- 
ratory, alimentary,  and  excretory  systems,  by  means  of  which 
all  the  tissues  are  supplied  with  the  materials  necessary  for  their 
life  and  growth,  and  relieved  of  all  those  waste  and  superfluous 
matters  which  are  the  results  of  their  activity.1 

All  the  tissues  of  the  body  are  traversed  by  minute  tubes, 
called  capillary  blood-vessels,  to  which  blood  is  brought  by 
large  tubes,  called  arteries,  and  from  which  blood  is  carried 
away  by  other  large  tubes,  called  veins.  These  capillaries  form 
networks,  the  meshes  of  which  differ  in  form  and  size  in  the 
different  tissues.  The  meshes  of  these  networks  are  occupied 
by  the  elements  (cells  or  fibres)  of  the  tissues ;  and  filling  up 
such  spaces  as  exist  between  the  capillary  walls  and  the  ele- 
ments of  the  tissue,  is  found  a  colourless  fluid,  resembling  in 
many  respects  the  fluid  portion  of  the  blood,  and  called  lymph. 
As  the  blood  flows  through  the  capillaries,  certain  constituents 
of  the  blood  pass  through  the  capillary  wall  into  the  lymph, 
and  certain  constituents  of  the  lymph  pass  through  the  capillary 
wall  into  the  blood  within  the  capillary.  There  is  thus  an 
interchange  of  material  between  the  blood  within  the  capillary 
and  the  lymph  outside.  A  similar  interchange  of  material  is  at 
the  same  time  going  on  between  the  lymph  and  the  tissue  itself. 

1  As  the  nervous  tissue  is  the  most  highly  organized  of  the  tissues,  and  its 
functions  are  very  complex  and  difficult  to  understand,  the  consideration  of  it  is 
deferred  until  the  student  has  mastered  the  vascular,  respiratory,  alimentary, 
and  excretory  systems. 

73 


74  ANATOMY  FOR   NURSES.  [CHAP.  VII. 

Hence,  by  means  of  the  lymph  acting  as  middleman,  a  double 
interchange  of  material  takes  place  between  the  blood  within 
the  capillary  and  the  tissue  outside  the  capillary.  In  every 
tissue,  so  long  as  life  lasts  and  the  blood  flows  through  the 
blood-vessels,  a  fluid  is  passing  from  the  blood  to  the  tissue,  and 
from  the  tissue  to  the  blood.  The  fluid  from  the  blood  to  the 
tissue  carries  to  the  tissue  the  material  which  the  tissue  needs 
for  building  itself  up  and  for  doing  its  work,  including  the 
all-important  oxygen.  The  fluid  from  the  tissue  to  the  blood 
carries  into  the  blood  certain  of  the  products  of  the  chemical 
changes  which  have  been  taking  place  in  the  tissue  —  products 
which  may  be  simply  waste,  to  be  cast  out  of  the  body  as  soon 
as  possible,  or  which. may  be  bodies  capable  of  being  made  use 
of  by  some  other  tissue.  The  tissues,  by  the  help  of  the  lymph, 
live  on  the  blood,  and  the  blood  may  thus  be  regarded  as  an 
internal  medium,  bearing  the  same  relations  to  the  tissue  that 
the  external  medium,  the  world,  does  to  the  whole  individual. 
Just  as  the  whole  organism  lives  on  the  things  around  it,  its 
air  and  its  food,  so  the  several  tissues  live  on  the  complex  fluid 
by  which  they  are  all  bathed,  and  which  is  to  them  their  imme- 
diate air  and  food. 

The  blood.  —  The  most  striking  external  feature  of  the  blood 
is  its  well-known  colour,  which  is  bright  red  approaching  to 
scarlet  in  the  arteries,  but  of  a  dark-red  or  purple  tint  in  the 
veins.  It  is  a  somewhat  sticky  liquid,  a  little  heavier  than 
water,  its  specific  gravity  being  about  1.055 ;  it  has  a  saltish 
taste,  a  slight  alkaline  reaction,  and  a  temperature  of  about 
100°  F. 

Seen  with  the  naked  eye  the  blood  appears  opaque  and  homo- 
geneous ;  but  when  examined  with  a  microscope  it  is  seen  to 
consist  of  a  transparent,  colourless  fluid,  with  minute  solid  par- 
ticles immersed  in  it.  The  colourless  fluid  is  named  plasma 
the  solid  particles  corpuscles.  These  corpuscles  are  of  two 
kinds,  the  red  or  coloured,  and  the  white  or  colourless.  In 
a  cubic  millimetre  1  of  healthy  blood  there  are  on  an  average 
5,000,000  red  corpuscles,  and  10,000  white.  The  number  of 
white  varies  much  more  than  that  of  the  red ;  the  proportion 
of  white  to  the  red  is  usually  given  at  from  1  to  250  up  to 
1  to  1000. 

1  A  millimetre  is  equal  to  0.039,  or  ^  of  an  English  inch. 


CHAP.  VII.]          THE   VASCULAR   SYSTEM. 


of  biconcave  disks. 
average  size  is 


Red  corpuscles  of  the  blood.  — The  red  corpuscles  have  a  nearly 
circular  outline  like  a  piece  of  coin,  and  most  of  them  have  a  shal- 
low, dimple-like  depres- 
sion on  both  sides  ;  their 
shape  is,  therefore,  that 
The 
of 

an  inch  in  diameter,  and 
about  one-fourth  that 
in  thickness.  When 
viewed  singly  by  trans- 
mitted light  the  col- 
oured corpuscles  do  not 
appear  red,  but  merely  of 
a  reddish-yellow  tinge, 
or  yellowish-green  in 
venous  blood.  It  is  only 

when    the     light    shines        FIG.  62.  -  RED   AND  WHITE  CORPUSCLES  OK 
Upon    a    number   of   COr-    THE  BLOOD-    Magnified.    A,  moderately  magnified, 
,  ,  ...  the  red  corpuscles  are  seen    in    rouleaux;    a,  a, 

pUSCleS  that  a  distinct  white  corpuscles;  B,  C,  D,  red  corpuscles,  highly 
red  colour  is  produced.  ma»nined»  seen  m  different  positions ;  E,  a  red  cor- 
puscle swollen  into  a  sphere  by  imbibition  of  water; 
F,  G,  white  corpuscles,  highly  magnified  ;  K,  white 


When    blood   is    drawn 


from  the  vessels,  the  red  corPuscle  treated  with  acetic  acid;  *  i>  «*i  COP- 

puscles  wrinkled  or  creuated. 

disks  sink  in  the  plasma: 

they  have  a  singular  tendency  to  run  together,  and  to  cohere 
by  their  broad  surfaces,  so  as  to  form  cylindrical  columns  like 
piles  or  rouleaux  of  coins,  and  the  piles  join  themselves  together 
in  an  irregular  network.  Generally  the  corpuscles  separate  on 
a  slight  impulse,  and  may  then  unite  again. 

Each  red  corpuscle  is  composed  of  an  external  colour/ess  enve- 
lope with  coloured  fluid  contents.  —  Quain. 

The  envelope  is  a  very  delicate  membrane  of  a  fatty  nature, 
and  may  be  ruptured  or  dissolved  under  certain  conditions. 
The  colour  of  the  fluid  contents  is  due  to  a  crystallizable  sub- 
stance called  haemoglobin.1  If  water  be  added  to  a  preparation 
of  blood  under  the  microscope,  the  water  passes  into  the  cor- 
puscle, and  the  concave  sides  of  the  corpuscle  become  bulged 
out  so  that  it  is  rendered  globular.  By  the  further  action  of 

1  Haemoglobin  is  a  proteid,  and  contains,  in  addition  to  the  usual  proteid 
elements,  a  certain  amount  of  iron. 


76  ANATOMY   FOE   NURSES.  [CHAP.  VIL 

water  the  haemoglobin  is  dissolved  out  of  the  corpuscle,  and 
the  colourless  envelope  remains  as  a  faint  circular  outline.  On 
the  other  hand,  the  addition  of  salt  to  a  preparation  of  blood  by 
absorbing  the  water  causes  the  corpuscles  to  shrink,  and  become 
wrinkled  or  crenated.  The  red  corpuscles  are  practically  small 
flattened  bags,  or  sacs,  the  form  of  which  may  be  changed  by 
altering  the  density  of  the  plasma.  They  are  very  soft,  flexible, 
and  elastic,  so  that  they  readily  squeeze  through  apertures  and 
passages  narrower  than  their  own  diameters,  and  immediately 
resume  their  proper  shape. 

Function  of  the  red  corpuscles.  —  The  red  corpuscles,  by  virtue 
of  their  haemoglobin,  are  emphatically  oxygen  carriers.  Ex- 
posed to  the  air  in  the  lungs,  the  haemoglobin  combines  with 
the  oxygen  present  in  the  air;  this  oxygen  the  haemoglobin 
carries  to  the  tissues ;  these,  more  greedy  of  oxygen  than  itself, 
rob  it  of  its  charge,  and  the  reduced  haemoglobin  hurries  back 
to  the  lungs  for  a  fresh  supply.  The  colour  of  the  blood  is 
dependent  upon  this  combination  of  the  haemoglobin  with  oxy- 
gen ;  when  the  haemoglobin  has  its  full  complement  of  oxygen, 
the  blood  has  a  bright  red  hue ;  when  the  amount  is  reduced,  it 
changes  to  a  dark  purplish  hue.  The  scarlet  blood  is  usually 
found  in  the  arteries,  and  is  called  arterial;  the  dark  purple 
in  the  veins,  and  is  called  venous  blood. 

White  corpuscles  of  the  blood.  —  The  white,  colourless  corpus- 
cles, or  leucocytes,  are  few  in  number  compared  with  the  red, 
and  both  on  this  account,  and  because  of  their  want  of  colour, 
they  are  not  at  first  easily  recognized  in  a  microscopic  prepara- 
tion of  blood.  Their  form  is  very  various,  but  when  the  blood 
is  first  drawn  they  are  rounded  or  spheroidal.  Measured  in  this 
condition  they  are  about  ^Q-Q-  of  an  inch  in  diameter.  The 
white  corpuscle  may  be  taken  as  the  type  of  a  free  animal  cell. 
It  is  a  small  piece  of  protoplasm,  containing  one  or  more  nuclei, 
and  has  no  limiting  membrane  or  cell-wall  (vide  Fig.  61  F.  G.). 

These  corpuscles,  or  cells,  possess  the  power  of  spontaneous 
movement,  and  are  capable  of  changing  their  form  and  place. 
While,  when  in  a  state  of  rest,  they  assume  in  general  the 
spheroidal  form,  we  find  that  when  they  become  active  they 
send  out  variously  shaped  processes,  some  fine  and  delicate, 
others  broad,  and  of  very  irregular  shape.  We  often  see,  after 
a  process  has  been  thrown  out,  that  it  becomes  larger  and 


CHAP.  VII.]          THE   VASCULAK   SYSTEM.  77 

larger,  the  cell  body  becoming  correspondingly  smaller,  until 
finally  the  whole  cell  passes  over  into  the  process,  thus  moving 
forward.  These  amoeboid  movements  are  always  very  slow, 
and  are  greatly  influenced  by  the  temperature,  density,  and 
amount  of  oxygen  in  the  fluid  in  which  the  cells  lie.  By  virtue 
of  this  locomotive  power  the  white  blood  cells  perform  certain 
evolutions  within  the  blood-vessels ;  they  escape  through  their 
walls,  and  sometimes  singly,  sometimes  in  vast  numbers,  move 
through  the  lymph  spaces  in  the  surrounding  tissues.  This  is 
spoken  of  as  the  "  migration  of  the  white  corpuscles."  In  an 
"inflamed  area"  large  numbers  of  white  corpuscles  are  thus 
drained  away  from  the  blood.  These  migrating  corpuscles,  or 
wander  cells,  may,  by  following  the  devious  tracks  of  the  lymph, 
find  their  way  back  into  the  blood;  some  of  them,  however, 
may  remain  and  undergo  various  changes.  Thus  in  inflamed 
areas,  when  suppuration  follows  inflammation,  the  white  cor- 
puscles which  have  migrated  may  become  "  pus  corpuscles." 

Again,  by  virtue  of  their  amoeboid  movements,  the  white 
corpuscles  can  creep  around  objects,  enveloping  them  with  their 
own  substance,  and  so  putting  them  inside  themselves.  As  an 
illustration  of  this  action  of  the  white  corpuscle,  we  may  state 
that,  according  to  some  observers  in  certain  diseases  in  which 
micro-organisms  make  their  appearance  in  the  blood,  the  white 
corpuscles  take  up  these  organisms  into  their  substance  and 
probably  exert  an  influence  over  them,  which  modifies  the 
course  of  the  disease  of  which  these  organisms  are  the  essen- 
tial cause. 

Furthermore,  the  white  corpuscles  are  not  only  capable  of 
taking  up  particles  in  the  blood,  but  are  also  capable  of  giving 
up  modified  products  to  the  blood,  and  it  follows  that  these 
metabolic  changes  must  necessarily  affect  the  composition  of  the 
fluid  plasma  in  which  they  lie. 

The  plasma  of  the  blood.  —  The  plasma  is  a  clear,  slightly 
yellowish  coloured  fluid,  consisting  for  the  most  part  of  water, 
holding  in  solution  or  suspension  proteid  substances,  fats, 
various  extractives,  and  saline  matters. 

The  proteid  substances  are  albumin,  para-globulin,  and  fibrin- 
ogen.  The  albumin  and  para-globulin  occur  in  about  equal 
quantities;  but  the  fibrinogen,  though  a  most  important  element 
in  the  blood,  occurs  in  very  small  quantities.  The  fats  are 


78  ANATOMY   FOR   NUESES.  [CHAP.  V1L 

scanty,  except  after  a  meal,  or  in  certain  diseased  conditions. 
The  extractives,  so  named  because  they  have  to  be  extracted  by 
special  methods  from  the  blood,  are  very  numerous.  The  most 
important  are  perhaps  urea,  lactic  acid,  and  sugar. 

The  saline  matters  are  the  chlorides  and  sodium  salts,  the 
phosphates  and  potassium  salts  being  found  chiefly  in  the 
corpuscles. 

Of  all  these  substances,  albumin  probably  holds  the  first  place 
in  regard  to  nutrition,  providing,  as  it  does,  the  greater  part  of 
the  material  necessary  for  the  daily  nourishment  and  renovation 
of  the  tissues.  In  this  process,  it  undergoes  a  variety  of  trans- 
formations by  which  it  is  converted  into  the  structural  charac- 
teristics of  the  tissues  which  it  supplies. 

Para-globulin  is  closely  allied  to  albumin  in  its  chemical  rela- 
tions, and  no  doubt  also  in  its  physiological  action.  Both  sub- 
stances are  coagulated  by  heat,  and  solidified  at  a  temperature 
of  160°  F. 

The  fibrinogen  of  the  plasma  is  the  substance  which  produces 
the  fibrin  of  coagulated  blood.  It  is  very  difficult  to  obtain 
in  the  fluid  condition,  owing  to  the  rapidity  with  which  it 
solidifies  when  blood  is  withdrawn  from  the  circulation. 

Of  the  mineral  salts,  the  sodium  chloride  is  the  most  abun- 
dant, constituting  nearly  40  per  cent  of  all  the  saline  ingredi- 
ents. The  mineral  salts  maintain  the  alkalescence  of  the  blood, 
a  property  which  is  essential  to  nutrition,  and  even  to  the 
immediate  continuance  of  life,  since  it  enables  the  plasma  to 
take  up  the  carbonic  acid  from  the  tissues  and  return  it  to  the 
lungs  for  elimination. 

The  clotting  of  blood.  —  Blood  when  drawn  from  the  blood- 
vessels of  a  living  body  is  perfectly  fluid.  In  a  short  time  it 
becomes  viscid,  and  this  viscidity  increases  rapidly  until  the 
whole  mass  of  blood  becomes  a  complete  jelly.  If  the  blood  in 
this  jelly  stage  be  left  untouched  in  a  glass  vessel,  a  few  drops 
of  an  almost  colourless  fluid  soon  make  their  appearance  on  the 
surface  of  the  jelly.  Increasing  in  number  and  running  together, 
the  drops  after  a  while  form  a  superficial  layer  of  pale  straw- 
coloured  fluid.  Later  on,  similar  layers  of  the  same  fluid  are 
seen  at  the  sides,  and  finally  at  the  bottom  of  the  jelly,  which, 
shrunk  to  a  smaller  size  and  of  firmer  consistency,  now  forms  a 
clot  or  crassamentum,  floating  in  a  perfectly  fluid  liquid.  The 


CHAP.  VIL]  THE   VASCULAR   SYSTEM.  79 

upper  surface  of  the  clot  is  generally  slightly  concave.  If  a 
portion  of  the  clot  be  examined  under  the  microscope,  it  is  seen 
to  consist  of  a  network  of  fine  fibrils  in  the  meshes  of  which 
are  entangled  the  red  and  white  corpuscles  of  the  blood.  The 
fibrils  are  composed  of  the  fibrin;  and  the  liquid  in  which 
the  clot  is  suspended  is  blood  minus  corpuscles  and  fibrin,  and 
is  called  serum.  The  clotting  of  the  blood  is  entirely  dependent 
upon  the  fibrin ;  for  if  fresh  blood,  before  it  has  time  to  clot,  be 
whipped  with  a  bundle  of  twigs,  the  fibrin  will  form  on  the 
twigs,  and  if  the  whipping  of  the  blood  be  continued  until  all 
the  fibrin  has  been  deposited  on  the  twigs,  the  blood  left  in  the 
vessel  will  be  found  to  have  lost  all  power  of  clotting. 

The  coagulation  of  blood  is  hastened  by  high  temperature, 
and  by  contact  with  any  rough  surface,  or  non-living  material. 
On  the  other  hand,  a  low  temperature  retards,  and  the  addition 
of  salt  in  sufficient  quantity  prevents,  coagulation.  After  death, 
the  blood  remains  a  long  time  fluid,  and  it  never  clots  so  firmly 
and  completely  as  when  shed.  It  clots  first  in  the  larger  vessels, 
but  not  until  several  hours  after  death  in  the  smaller  vessels. 

The  coagulability  of  the  blood  differs  in  different  individuals, 
and  in  rare  cases  is  so  slight  that  the  most  trivial  operation  in- 
volving hemorrhage  is  attended  with  great  danger. 

The  quantity  of  blood  contained  in  the  body  is  a  balance 
struck  between  the  tissues  which  give  to,  and  those  which  take 
away  from,  the  blood.  Thus  the  tissues  of  the  alimentary  canal 
largely  add  to  the  blood  water  and  the  material  derived  from 
food,  while  the  excretory  organs  largely  take  away  water  and 
the  other  substances  constituting  the  excretions.  From  the 
result  of  a  few  observations  on  executed  criminals,  it  has  been 
concluded  that  the  total  quantity  of  blood  in  the  human  body  is 
about  Jg-  of  the  body  weight. 

General  composition  of  the  blood.  —  Not  only  do  the  several  tis- 
sues take  up  from  the  blood  and  give  up  to  the  blood  different 
things  at  different  rates  and  at  different  times,  but  all  the 
tissues  take  up  oxygen  and  give  up  carbonic  acid  in  varying 
quantities.  From  this  it  follows,  on  the  one  hand,  that  the 
composition  and  character  of  the  blood  must  be  forever  varying 
in  different  parts  of  the  body ;  and,  on  the  other  hand,  that  the 
united  action  of  all  the  tissues  must  tend  to  establish  and  main- 
tain an  average  uniform  composition  of  the  whole  mass  of  blood. 


80  ANATOMY   FOR   NURSES.  [CHAP.  VII. 

To  sum  up  briefly,  the  blood  is  composed  of  — 

Proteid  substances. 

Fats. 
PLASMA        •  •«, 

Extractives. 

Salts. 
rRed 
CORPUSCLES  j  and 

I  White. 

The  plasma  is  chiefly  the  carrier  of  nutriment  to  the  tissues, 
and  of  waste  matter  from  the  tissues.  The  red  corpuscles  are 
pre-eminently  the  carriers  of  oxygen ;  the  white  corpuscles  may 
be  regarded  as  scavengers,  as  important  protective  elements  in 
many  diseases,  and  possibly  as  contributors  to  the  construction 
of  new  tissue  where  such  has  been  injured  or  destroyed. 

NOTE.  —  When  we  remember  that  the  tissues  live  on  the  blood,  we  recognize 
the  gravity  of  those  diseased  conditions  in  which  important  elements  are  being 
constantly  drained  away  from  the  blood,  as,  for  example,  the  albumin  in  dis- 
eases of  the  kidneys,  the  red  corpuscles  in  hemorrhage,  the  water  of  the  blood 
in  cholera,  etc.  Withdrawal  of  oxygen,  as  we  all  know,  causes  instant  death, 
and  a  constant  supply  of  fresh  air  is  a  vital  necessity  of  life.  Nor  is  it  of  less 
importance  that  the  blood  be  kept  free  from  those  waste  matters,  — pre-eminently 
carbonic  acid  and  urea,  —  which,  in  accumulating,  poison  the  system,  and,  if 
not  excreted  in  sufficient  amount,  will  as  surely  cause  death  as  the  withdrawal 
from  the  blood  of  any  of  its  most  vital  constituents. 


CHAPTER  VIII. 

THE  VASCULAR  SYSTEM  CONTINUED:   HEART;   ARTERIES; 
VEINS;   CAPILLARIES. 

THE  blood,  as  we  have  said,  is  the  internal  medium  on  which 
the  tissues  live.  It  is  carried  through  the  body  by  branched 
tubes  named  blood-vessels.  It  is  driven  along  these  tubes  by 
the  action  of  the  heart,  which  is  a  hollow  muscular  organ  placed 
in  the  centre  of  the  vascular  system.  One  set  of  vessels — the 
arteries  —  conducts  the  blood  out  from  the  heart  and  distributes 
it  to  the  different  parts  of  the  body,  whilst  other  vessels  —  the 
veins  —  bring  it  back  to  the  heart  again.  The  blood  from  the 
arteries  gets  into  the  veins  by  passing  through  a  network  of 
fine  tubes  which  connect  the  two,  and  which  are  named,  on 
account  of  their  small  size,  the  capillary  (i.e.  hair-like)  vessels. 

All  the  tissues,  with  the  exception  of  the  epithelial  tissue, 
and  most  of  the  cartilages,  are  traversed  by  these  networks  of 
capillary  vessels.  It  is  through  the  thin  walls  of  the  capillaries 
that  the  interchange  of  material  which  is  continually  going  on 
between  the  blood  and  the  tissues  takes  place.  It  is  in  the 
capillaries,  then,  that  the  chief  work  of  the  blood  is  done ;  and 
the  object  of  the  vascular  mechanism  is  to  cause  the  blood  to 
flow  through  these  vessels  in  the  manner  best  adapted  for 
accomplishing  this  work. 

The  use  of  the  arteries  is  to  carry  and  regulate  the  supply  of 
blood  from  the  heart  to  the  capillaries ;  the  use  of  the  veins,  to 
carry  the  blood  from  the  capillaries  back  to  the  heart ;  the  use 
of  the  heart,  to  drive  the  blood  in  a  suitable  manner  through 
the  arteries  into  the  capillaries,  and  from  the  capillaries  back 
along  the  veins  to  itself  again.  We  shall  see  that  the  structure 
of  these  several  parts  is  adapted  to  these  several  uses. 

The  heart.  —  The  heart  is  a  hollow  muscular  organ,  divided 

G  81 


82 


ANATOMY   FOE,   NUKSES.          [CHAP.  VIII. 


by  a  longitudinal  partition  into  a  right  and  a  left  heart,  each  of 
which  is  subdivided  by  a  transverse  constriction  into  two  com- 
partments, an  upper  and  a  lower,  which  communicate  with  each 

other.  Its  general  form 
is  that  of  a  blunt  cone. 
It  is  situated  in  the 
thorax,  between  the 
lungs,  and,  together 
with  the  adjacent  parts 
of  the  great  blood-ves- 
sels which  carry  blood 
to  and  from  it,  is  en- 
closed in  a  membranous 
covering,  the  pericar- 
dium. The  heart  lies 
nearer  to  the  front 
than  to  the  back  of  the 
chest,  and  is  placed  be- 

FIG.  63.  — THE  HEART  AND  LUNGS.    1,  right  ven-   ,  .     ,     ,  , 

tricle;  3,  right  auricle;  6,  7,  pulmonary  artery;  9,    nmd 
aorta;    10,  superior  vena  cava;   11,  innominate  ar- 
tery ;  12,  right  subclavian  vein  ;  14,  innominate  vein ; 
15,  left  common  carotid;  17,  trachea;  20,  pulmonary 
veins ;  22  to  25,  lungs,  partially  turned  back  to  show    "base  bein  Q  directed  UD- 
veins  on  left  side. 

wards,  backwards,  and 

to  the  right,  while  the  pointed  end  or  apex  points  downwards, 
forwards,  and  to  the  left.  The  impulse  of  the  heart  against  the 
wall  of  the  chest  is  felt  in  the  space  between  the  fifth  and  sixth 
ribs,  a  little  below  and  to  the  inner  side  of  the  left  nipple.  It 
has,  therefore,  a  very  oblique  position  in  the  chest.  It  is  sus- 
pended and  kept  in  position  by  the  great  vessels  at  the  base, 
and  is  also  supported  by  the  diaphragm.  According  to  Laennec, 
the  heart  in  its  normal  condition  is  about  equal  in  size  to  the 
fist  of  the  individual  to  whom  it  belongs. 

The  main  substance  of  the  heart  is  composed  of  muscular 
tissue.  Between  the  muscle  fibres  is  a  certain  amount  of  in- 
terstitial tissue  with  numerous  blood-vessels  and  lymphatics, 
and,  in  some  parts,  nerves  and  ganglia.  There  is  also  a  consid- 
erable amount  of  fat,  chiefly  collected  at  the  base  of  the  heart 
and  beneath  the  pericardium.  The  muscular  tissue  of  the  heart 
differs  from  all  other  involuntary  muscular  tissue  in  possessing 
transverse  striae.  The  fibres  continually  branch  and  unite  with 


costal    cartilages, 
broader     end     or 


CHAP.  VIII.]         THE   VASCULAK   SYSTEM. 


83 


one  another  so  as  to  form  a  kind  of  network  or  sponge-like  sub- 
stance. The  arrangement  of  the  fibres  differs  in  the  auricles 
and  the  ventricles,  and  is  very  intricate ;  the  fibres  run  trans- 
versely, longitudinally,  obliquely,  and  in  the  apex  of  the  ven- 
tricles take  a  spiral  turn 
or  twist.  The  muscular 
walls  of  the  auricles  are 
much  thinner  than  those 
of  the  ventricles,  and  the 
wall  of  the  left  ventricle 
is  thicker  than  that  of  the 
right.  This  difference  in 
bulk  is  to  be  accounted 
for,  as  we  shall  see  later 
on,  by  the  greater  amount 
of  work  the  ventricles,  as 
compared  with  the  auri- 
cles, have  to  do.  The 
muscular  walls  of  the 
heart  are  abundantly 
supplied  with  blood 
and  lymph.  The  nerves  FIG.  64.  — ANTERIOR  VIEW  OF  HEART,  DIS- 
whioh  mirmlv  thp  hpart  SECTED>  AFTER  LONG  BOILING,  TO  SHOW  THE 
>uppiy  G  SUPERFICIAL  MUSCULAR  FIBRES.  (Allen  Thorn- 

are    partly    derived    from    son.)     The  aorta  (&')  and  pulmonary  artery  (a') 
,1  i  •       i  have  been  cut  short  close  to  the  semilunar  valves. 

the  cerebro-spmal  system,  a>  right  ventricle.  6>  left  ventricie:  c,c,  groove 

and  partly  from  the  Sym-  between  ventricles ;  d,  d',  right  auricle ;  e,  e',  left 

,|     ,.  p  auricle;  /,  superior  vena  cava;  g',  g",  right  and 

patnetl         System.        l^On-  ]eft  pUimonary  veins.     The  fibres  are  seen  run- 

nected     with     the     lierve  niuS  in  a  circular,  oblique,  transverse,  and  longi- 

^.,  ,    .  ,  tudinal  direction. 

fibres  supplying  the  heart 

are  groups  of  nerve  cells,  or  ganglia. 

The  heart  is  covered,  as  mentioned  above,  by  a  membranous 
covering  in  the  form  of  a  sac.  This  membranous  sac,  or  peri- 
cardium, is  one  of  the  serous  membranes  of  the  body.1  It  is  a 
sort  of  double  bag ;  one  half  of  the  bag,  called  the  visceral  por- 
tion (viscus,  organ),  is  closely  adherent  to  the  heart  substance, 
and  also  covers  the  great  blood-vessels  for  about  an  inch  and  a 
half  from  the  base  of  the  heart ;  the  other  half,  the  parietal 
portion,  is  continuous  with,  and  reflected  over,  the  visceral  por- 
tion, so  that  it  loosely  envelops  both  it  and  the  heart. 
1  See  note  on  serous  membranes  at  end  of  chapter. 


84  ANATOMY  FOR   NURSES.  [CHAP.  VIII. 

The  pericardium  forms  a  completely  closed  sac ;  its  internal 
surfaces  are  very  smooth  and  polished,  they  are  lined  by  epithe- 
lium, and  secrete  a  small  quantity  of  serous  fluid.  As  their 
opposing  surfaces,  owing  to  the  constant  contractions  of  the 
heart,  are  continually  sliding  one  upon  the  other,  they  are  ad- 
mirably constructed  to  protect  the  heart  from  any  loss  of  power 
by  friction. 

The  interior  of  the  heart  is  lined  by  a  delicate,  smooth  mem- 
brane, called  the  endocardium.  This  pavement  membrane  lines 
all  the  cavities  of  the  heart,  and  is  continued  into  the  blood- 
vessels, forming  their  innermost  coat. 

The  cavities  of  the  heart.  —  The  heart  is  divided  from  the  base 
to  the  apex,  by  a  fixed  partition,  into  a  right  and  left  half. 

The  two  sides  of  the  heart 
have  no  communication  with 
each  other:  the  right  side  al- 
ways contains  venous,  and  the 
left  side  arterial,  blood.  Each 
half  is  subdivided  into  two 
cavities,  the  upper,  called  au- 
ricle ;  the  lower,  ventricle. 
These  cavities  communicate 
with  one  another  by  means  of 
constricted  openings,  the  auric- 
ulo-ventricular  orifices,  which 
are  strengthened  by  fibrous 
FIG.  65. -RIGHT  'SIDE  OF  HEA^  i,  rings,  and  protected  and  guard- 

cavity  of  right  auricle ;  3,  vena  cava  supe-  ed  by  valves.     The  valve  guard- 

rior;  4,  vena  cava  inferior;  9,  entrance  of  ,•  •    i  j  i  ,    • 

auriculo-ventricular  opening ;«,  right  ven-  mg  the   nght  aunculo,ventriC- 

tricle;   6,  c,  cavity  of  right  ventricle,  on  ular    opening    is    Composed    of 

the  walls  of  which  the  columnse  carnse  ,-t  ,    •  -,         n  ,    . 

are  seen;   d,  pulmonary  artery;    e,  /,  tri-  three    triangular    flaps,    and    IS 

cuspid  valve;  z,columnae  carnse;  m,  semi-  hence    named   tricuspid.        The 

lunar  val ve ;  o, left  ventricle;  p,  ascending  n  .    ,         ~ 

aorta;  q,  arch;  r,  descending  aorta.  naPs     are     mainly    formed     of 

fibrous  tissue  covered  by  endo- 
cardium. At  their  bases  they  are  continuous  with  one  another, 
and  form  a  ring-shaped  membrane  around  the  margin  of  the  auric- 
ular opening :  their  pointed  ends  are  directed  downwards,  and 
are  attached  by  cords,  the  chordce  tendinece,  to  little  muscular 
pillars  provided  in  the  interior  of  the  ventricles  for  this  purpose. 
The  valve  guarding  the  left  auricular  opening  consists  of  only 


CHAP.  VIII.]          THE   VASCULAR   SYSTEM. 


85 


FIG.  66. — LEFT  SIDE  OF  HEART.     1,  cavity 

drives  the  flaps  backwards    of  left  auricle;  3'  opening  of  right 


two  flaps,  and  is  named  the  bicuspid,  or  mitral  valve.  It  is 
attached  in  the  same  manner  as  the  tricuspid  valve,  which  it  close- 
ly resembles  in  structure, 
except  that  it  is  much 
stronger  and  thicker  in 
all  its  parts. 

These  valves  oppose  no 
obstacle  to  the  passage  of 
the  blood  from  the  auri- 
cles into  the  ventricles ; 
but  any  flow  forced  back- 
wards gets  behind  the 
flaps  of  the  valve  (be- 
tween the  flap  and  the 
wall  of  the  ventricle)  and 

veins ;  5,  left  pulmonary  veins ;  6,  auriculo-ven- 
and  Upwards,  Until,  meet-  tricular  opening;  8,  left  ventricle;  9,9,  cavity  of 
,  ,  left  ventricle;  a,  mitral  valve,  its  flaps  are  at- 

ing  at  their  edges,  tney  tached  by  the  chorda?  tendinese  to  b,  b,  the  mus- 
Ullite  and  form  a  com-  cu^ar  pillars,  or  colunmae carnse ;  d,  arch  of  aorta; 

e,  pulmonary  artery. 

plete  transverse  partition 

between   the    ventricle    and   auricle.      Being   retained   by  the 

chordae  tendinese,  the  expanded  flaps  of  the  valve  resist  any 

pressure  of  the  blood 
which  might  otherwise 
force  them  back  to  open 
into  the  auricle  ;  the  mus 
cular  pillars,  also,  to 
which  the  chordae  tendi- 
neae  are  attached,  contract 
and  shorten  at  the  same 
time,  and  thus  help  to 
keep  them  taut. 

Beside  the  openings  be- 
tween the  auricles  and 
ventricles,  each  auricle 
has  two  or  more  veins 
opening  into  it,  and  each 
ventricle  has  a  large  ar- 
tery opening  out  of  it. 

The  openings  of  the  veins  do  not  require  valves,  but  both  the 


FIG.  67.  —  SECTION  OF  HEART  AT  LEVEL  OF 
VALVES.  P,  pulmonary  artery;  A,  aorta;  M, 
mitral  valve ;  T,  tricuspid  valve. 


86  ANATOMY   FOR   NURSES.          [CHAP.  VIII. 

arterial  openings  are  provided  with  a  set  of  valves.  These  valves, 
called  semilunar  valves,  consist  of  three  semicircular  flaps,  each 
flap  being  attached  by  its  convex  border  to  the  inside  of  the 
artery  where  it  joins  the  ventricle,  while  its  other  border  projects 
into  the  interior  of  the  vessel.  The  flaps  of  these  valves  form  a 
complete  barrier,  when  closed,  to  the  passage  of  the  blood  from 
the  arteries  into  the  heart,  but  offer  no  resistance  to  the  flow 
from  the  heart  into  the  arteries. 

The  beat  of  the  heart.  —  So  long  as  life  lasts,  the  muscular 
tissue  of  the  heart  contracts  and  relaxes  unceasingly.  We  may 
call  the  heart  a  muscular  pump,  the  force  of  whose  strokes  is 
supplied  by  the  contraction  of  muscular  fibres,  the  strokes 
being  repeated  so  many  times  a  minute.  It  is  constructed  and 
furnished  with  valves  in  such  a  way  that,  at  each  stroke,  it 
drives  a  certain  quantity  of  blood  with  a  certain  force  and  a 
certain  rapidity  from  the  ventricles  into  the  arteries,  receiving, 
during  the  stroke,  and  the  interval  between  that  stroke  and 
the  next,  the  same  quantity  of  blood  from  the  veins  into 
the  auricles. 

The  contractions  of  the  heart  are  rhythmical ;  that  is  to  say, 
they  occur  in  a  certain  order.  First,  there  is  a  simultaneous 
contraction  of  the  walls  of  both  auricles ;  immediately  following 
this,  a  simultaneous  contraction  of  both  ventricles ;  then  comes 
a  pause,  or  period  of  rest,  after  which  the  auricles  and  ven- 
tricles contract  again  in  the  same  order  as  before,  and  their 
contractions  are  followed  by  the  same  pause  as  before.  The 
state  of  contraction  of  the  heart  is  called  the  systole ;  the  state 
of  relaxation  and  dilatation,  its  diastole. 

If  the  chest  of  an  animal  be  opened  and  artificial  respiration 
kept  up,  the  heart  may  be  watched  beating,  and  a  complete  beat 
of  the  whole  heart  may  be  observed  to  take  place  as  follows :  — 

The  great  veins  are  seen,  while  full  of  blood,  to  contract  in 
the  neighbourhood  of  the  heart,  the  wave  of  contraction  running 
on  towards  the  auricles,  increasing  in  intensity  as  it  goes. 
Arrived  at  the  auricles,  which  are  now  full  of  blood,  the  wave 
of  contraction  passes  on  to  them,  and  they  contract  suddenly 
and  quickly.  During  this  contraction,  the  walls  of  the  auricles 
press  towards  the  auriculo-ventricular  orifices,  and  the  blood 
passes  over  the  tricuspid  and  mitral  valves  into  the  ventricles. 
The  ventricles  fill  rapidly,  and  as  soon  as  the  auricular  systole 


CHAP.  VIII.]         THE   VASCULAR   SYSTEM.  87 

is  over,  they  are  also  seen  to  contract,  their  walls  becoming  very 
tense  and  hard;  the  apex  is  tilted  upwards,  and  the  heart 
twists  somewhat  on  its  own  axis.  During  the  ventricular 
systole,  the  blood  in  the  ventricles  is  forced  through  the  semi- 
lunar  valves  into  the  arteries,  which  are  seen  to  elongate  and 
expand  as  the  blood  is  pumped  into  them. 

The  work  of  the  auricles  and  ventricles  is  very  unequal. 
All  the  auricles  have  to  do  is  to  pump  the  blood  into  the  ven- 
tricles, which  at  the  time  are  nearly  empty  cavities  with  relaxed 
and  flaccid  walls.  The  ventricles,  on  the  contrary,  have  to 
pump  the  blood  into  tubes  which  are  already  full ;  and  if  there 
were  no  auriculo-ventricular  valves,  the  blood  would  meet  with 
less  resistance  in  pushing  its  way  backward  into  the  auricles 
than  in  pushing  open  the  semilunar  valves  and  forcing  its  way 
into  the  arteries. 

Hence  the  necessity,  firstly,  of  the  tricuspid  and  mitral 
valves;  and,  secondly,  of  the  superior  thickness  and  strength 
of  the  walls  of  the  ventricles,  as  compared  with  those  of  the 
auricles;  and  since  the  left  side  of  the  heart  has  a  larger 
system  of  blood-vessels  to  supply,  and  more  resistance  to  over- 
come than  the  right  side,  it  follows  that  the  left  ventricle  needs 
a  thicker  muscular  wall  than  the  right. 

The  beat  of  the  heart  is  caused  by  the  rhythmical  contractions 
of  its  muscular  fibres.  Whether  these  contractions  are  auto- 
matic, or  dependent  upon  the  ganglia  lodged  in  the  cardiac 
muscular  tissue,  is  uncertain.  That  the  contractions  of  the 
heart  do  not  depend  upon  the  general  nervous  system  is  cer- 
tain, for  the  heart  will  continue  to  beat  for  some  little  time 
after  its  removal  from  the  body.  It  probably  depends  upon 
complex  metabolic  changes,  not  yet  clearly  understood. 

The  character  of  the  beat,  however,  is  governed  and  regulated 
by  two  sets  of  nerves.  The  first  set  come  from  the  cerebro-spinal 
centre,  and  are  supplied  by  the  pneumogastric  nerves.  They 
are  the  inhibitory  fibres ;  that  is  to  say,  they  slow  and,  with  a 
strong  stimulation,  will  stop  for  a  short  time  the  action  of  tlic 
heart.  They  weaken  the  systole,  and  prolong  the  diastole. 
The  other  set  come  from  the  sympathetic  nerves,  and  are  accel- 
erating fibres  which,  upon  stimulation,  increase  not  only  the 
rapidity,  but  the  force  of  the  beat.  The  diastole  is  shortened, 
and  the  systole  strengthened. 


88 


ANATOMY   FOR   NURSES.          [CHAP.  VIII. 


The  sounds  of  the  heart.  —  If  the  ear  be  applied  over  the  heart, 
certain  sounds  are  heard,  which  recur  with  great  regularity. 
The  first  sound  is  a  comparatively  long,  booming  sound;  the 
second,  a  short,  sharp,  sudden  one.  Between  the  first  and 
second  sounds,  the  interval  of  time  is  very  short,  too  short  to 
be  measurable ;  but,  between  the  second  arid  the  succeeding  first 
sounds  there  is  a  distinct  pause.  The  first  sound  is  generally 
supposed  to  be  caused  by  the  contraction  of  the  ventricular 
walls ;  the  second  sound  is  undoubtedly  caused  by  the  sudden 
closure  of  the  semilunar  valves. 

These  sounds  in  certain  diseases  of  the  heart  become  changed 
and  obscure,  and  are  replaced  by  various  distinctive  and  charac- 
teristic murmurs. 

The  arteries.  —  An  artery  is  usually  described  as  being  com- 
posed of  three  coats,  —  an  inner  or 
elastic,  a  middle  or  muscular,  and 
an  external  or  areolar. 

The  inner  coat  of  an  artery  con- 
sists of  two  layers :  the  inner  layer 
is  composed  of  pavement  epithe- 
lium, and  forms  a  smooth  lining  for 
the  tube ;  the  outer  layer  is  a  fine 
network  of  elastic  connective  tissue 
fibres. 

The  middle  or  muscular  coat  con- 
sists mainly  of  circularly  disposed 
plain  muscular  fibres.  It  has  also 

FIG.  68.  —  STRUCTURE   OF  AN     •  ,   -,  ^  <•     i 

ARTERY.    (Ledig.)    A,  internal    m  most  large  arteries  layers  of  elas- 
coat,  with  b,  its  inner  layer  of    tic  fibres,  which  form  close   felted 

pavement   epithelium;    c,    middle  1^.1^1  _<•        ,1 

coat,  with  transverse  fibres;  a,    networks,  the  fibres  running  for  the 
outer    coat,    with    longitudinal    mOst  part  in  an  oblique  and  longitu^ 

fibres.  .*:. 

dmal  direction. 

The  outer  coat  is  formed  of  areolar  tissue,  mixed  with  which 
are  a  good  many  elastic  fibres.  The  strength  of  an  artery 
depends  largely  upon  this  coat ;  it  is  far  less  easily  cut  or  torn 
than  the  other  coats,  and  it  serves  to  resist  undue  expansion  of 
the  vessel.  The  arteries  are  also  protected  by  sheaths  of  con- 
nective tissue,  which  surround  and  blend  with  the  outer  coat. 

By  virtue  of  their  structure,  the  arteries  are  both  contractile 
and  elastic.  The  proportion  of  the  muscular  and  elastic  ele- 


CHAP.  VIII.]         THE   VASCULAR   SYSTEM.  89 

ments  differs  in  different  arteries ;  but,  as  a  general  rule,  the 
larger  arteries  are  the  more  elastic,  and  the  smaller  the  more 
muscular.  The  elasticity  and  contractility  of  the  arteries  may 
be  demonstrated  by  the  following  example :  - 

If  we  tie  a  piece  of  a  large  artery  at  one  end  and  inject  fluid 
into  the  other  end,  the  artery  swells  out  to  a  very  great  extent, 
but  will  return  at  once  to  its  former  size  when  the  fluid  is  let 
out.  This  great  elasticity  of  the  arteries  adapts  them  for 
receiving  the  additional  amount  of  blood  thrown  into  them 
at  each  contraction  of  the  heart.  Again,  if  we  stimulate  the 
muscular  coat  of  any  of  the  smaller  arteries,  the  artery  will 
shrink  in  size,  the  circularly  disposed  fibres  contracting  and 
narrowing  the  calibre  of  the  vessel.  This  contractility  is  under 
the  control  of  the  nervous  system,  and  as  the  organs  of  the 
body  that  are  at  rest  do  not  require  so  much  blood  as  those  that 
are  working  actively,  the  nervous  system,  the  master-regulator 
of  the  body's  work,  is  able  to  diminish  or  increase  the  supply  of 
blood  to  the  capillaries  in  different  parts  by  acting  upon  this 
contractile  muscular  tissue  in  the  arterial  walls.  The  arteries 
do  not  collapse  when  empty;  and  when  an  artery  is  severed, 
the  orifice  remains  open.  The  muscular  coat,  however,  con- 
tracts somewhat  in  the  neighbourhood  of  the  opening,  and  the 
elastic  fibres  cause  the  artery  to  retract  a  little  within  its 
sheath.1 

The  walls  of  the  arteries  are  supplied  with  both  blood-vessels 
and  nerves.  The  blood-vessels  are  known  as  the  vaso-vasorum 
vessels  and  the  nerves  as  the  vaso-motor  nerves. 

The  veins.  —  The  veins  have  three  coats,  and  on  the  whole 
resemble  the  arteries  in  structure.  They  differ  from  them, 
however,  in  having  much  thinner  walls,  and  in  their  walls  con- 
taining relatively  much  more  white  fibrous  tissue  and  much  less 
yellow  elastic  tissue.,  They  are,  therefore,  not  so  elastic  or  con- 
tractile as  the  arteries,  and  their  walls  collapse  when  empty. 
Many  of  the  veins,  especially  those  of  the  limbs,  are  provided 
with  valves,  which  are  mechanical  contrivances  adapted  to  pre- 
vent the  reflux  of  the  blood.  The  valves  are  semilunar  folds  of 
the  internal  coat  of  the  veins ;  the  convex  border  is  attached  to 
the  side  of  the  vein,  and  the  free  edge  points  towards  the  heart. 

1  This  property  of  the  severed  artery  is  an  important  factor  in  the  arrest  of 
hemorrhage. 


90  ANATOMY   FOR   NURSES.          [CHAP.  VIII. 

Should  the  blood  in  its  onward  course  towards  the  heart  be,  for 
any  reason,  driven  backwards,  the  refluent  blood,  getting  be- 
tween the  wall  of  the  vein  and  the  flaps  of 
the  valve,  will  press  them  inwards  until 
their  edges  meet  in  the  middle  of  the  chan- 
nel and  close  it  up.  The  valves  have 
usually  two  flaps,  sometimes  one,  and 
rarely  three.  The  veins,  like  the  arteries, 
are  supplied  with  both  blood-vessels  and 
nerves,  the  supply,  however,  being  far  less 
abundant. 

The  capillaries.  —  The  walls  of  the  cap- 
illaries  are  formed  entirely  of  a  layer  of 
pairs  of  valves;  B,  longi-  simple  epithelium  composed  of   flattened 

tudinal    section    of    vein,         ,,       .    .        ,        1  11  u 

showing  valves  closed.         cells  joined  edge  to  edge  by  cement  sub- 
stance,   and    continuous    with    the    layer 

which  lines  the  arteries  and  veins.  The  capillaries  commu- 
nicate freely  with  one  another  and  form  interlacing  networks 
of  variable  form  and  size  in  the  different  tissues.  Their 
average  diameter  is  so  small  that  only  two  or  three  blood- 
corpuscles  can  pass  through  them  abreast,  and  in  many  parts 
they  lie  so  closely  together  that  a  pin's  point  cannot  be  in- 
serted between  them.  They  are  most  abundant,  and  form  the 
finest  networks  in  those  organs  where  the  blood  is  needed  for 
other  purposes  than  local  nutrition,  such  as,  for  example,  for 
secretion  or  absorption.  In  the  glandular  organs  they  supply 
the  substances  requisite  for  secretion;  in  the  intestines  they 
take  up  the  elements  of  digested  food ;  in  the  lungs  they  absorb 
oxygen  and  give  up  carbonic  acid ;  in  the  kidneys  they  discharge 
the  waste  products  collected  from  other  parts ;  all  the  time,  every- 
where through  their  walls,  that  interchange  is  going  on  which  is 
essential  to  the  renovation,  growth,  and  life  of  the  whole  body. 
It  must  be  remembered  that  although  the  arteries,  veins,  and 
capillaries  have  each  the  distinctive  structure  above  described, 
it  is  at  the  same  time  difficult  to  draw  the  line  between  the 
smaller  artery  and  larger  capillary,  and  between  the  larger 
capillary  and  smallest  vein.  The  veins  on  leaving  the  capillary 
networks  only  gradually  assume  their  several  coats,  while  the 
arteries  dispense  with  their  coats  in  the  same  imperceptible  way 
as  they  approach  the  capillaries. 


CHAP.  VI1L]         THE   VASCULAR   SYSTEM. 


91 


Serous  membranes.  —  Serous  membranes  are  thin  and  transparent,  tol- 
erably strong,  extensile,  and  elastic.  They  are  lined  on  the  inner  surface  by 
a  simple  epithelial  layer  of  flattened  cells  (endothelium).  The  surfaces  are 
moistened  by  a  fluid  resembling  serum,  and  from  which  the  membranes 
obtain  their  name  of  serous  membranes.  Here  and  there  between  the  cells 


FIG.  70.  —  PORTION  OF  ENDOTHELIUM  OF  PERITONEUM.     (Klein.)     a,  larger  cells; 
6,  smaller  ones,  with  here  and  there  a  pseudo-stoma  between. 

openings  are  seen,  which  are  of  two  kinds.  The  smaller  and  more  numerous 
are  false  openings,  and  are  termed  pseudo-stomata ;  the  larger  or  true  aper- 
tures are  termed  stornata,  and  open  into  subjacent  lymphatics.  The  sub- 
stance of  serous  membranes  underneath  the  endothelium  is  composed  of 
a  network  of  connective  tissue  containing  a  variable  amount  of  white 
and  elastic  fibres.  Where  the  membrane  is  thick,  this  ground  substance 
contains  blood-vessels  and  lymphatics,  the  lymphatics  being  exceedingly 
abundant. 

Serous  membranes  form  closed  sacs,  one  part  of  which  is  attached  to  the 
walls  of  the  cavity  which  it  lines,  —  the  parietal  portion,  —  whilst  the  other 
is  reflected  over  the  surface  of  the  organ  or  organs  contained  in  the  cavity, 
and  is  named  the  visceral  portion  of  the  membrane.  In  this  way  the  viscera 
are  not  contained  within  the  sac,  but  are  really  placed  outside  of  it,  and 
some  of  the  organs  may  receive  a  complete,  while  others  receive  only  a  par- 
tial or  scanty  investment. 

In  passing  from  one  part  to  another  the  membrane  frequently  forms 
folds,  some  of  which  are  designated  by  special  names,  such  as  the  mesen- 
tery, meso-colon,  and  omentum. 

The  chief  serous  membranes  are  the  peritoneum,  the  largest  of  all,  lining 
the  cavity  of  the  abdomen ;  the  two  pleurae,  lining  the  chest  and  covering 
the  lungs ;  the  pericardium,  covering  the  heart. 


92  ANATOMY   FOE,  NUKSES.          [CHAP.  VIII. 

The  peritoneum  in  the  female  is  an  exception  to  the  rule  that  serous 
membranes  are  perfectly  closed  sacs,  as  it  has  two  openings  by  which  the 
Fallopian  tubes  communicate  with  its  cavity. 

The  inner  surface  of  a  serous  membrane  is  free,  smooth,  and  polished ; 
the  inner  surface  of  one  part  is  applied  to  the  corresponding  inner  surface 
of  some  other  part,  a  very  small  quantity  of  fluid  only  being  interposed 
between  the  surfaces.  The  organs  situated  in  a  cavity  lined  by  a  serous 
membrane,  being  themselves  also  covered  by  it,  can  thus  glide  easily  against 
its  walls  or  upon  each  other,  their  motions  being  rendered  smoother  by  the 
lubricating  fluid. 


CHAPTER  IX. 

THE  VASCULAR   SYSTEM   CONTINUED :    ARTERIAL   DISTRIBUTION 
AND   VENOUS   RETURN. 

The  arteries.  —  The  arteries,  which  carry  and  regulate  the 
supply  of  blood  from  the  heart  to  the  capillaries,  are  distributed 
throughout  the  body  in  a  systematic  manner,  and  before  taking 
up  the  circulation  we  must  try  to  gain  a  general  idea  of  this 
system  of  distribution,  in  order  that  we  may  be  able  to  locate 
the  position  of  these  important  vessels.  The  arteries  usually 
occupy  protected  situations,  that  they  may  be  exposed  as  little 
as  possible  to  accidental  injury.  As  they  proceed  in  their 
course  they  divide  into  branches,  the  division  taking  place  in 
different  ways.  An  artery  may  at  once  resolve  itself  into  two 
or  more  branches,  no  one  of  which  greatly  exceeds  the  rest  in 
size ;  or  it  may  give  off  several  branches  in  succession,  and  still 
maintain  its  character  as  a  trunk.  An  artery,  after  a  branch 
has  gone  off  from  it,  is  smaller  than  before,  but  usually  con- 
tinues uniform  in  diameter  until  the  next  secession.  A  branch 
of  an  artery  is  less  in  diameter  than  the  trunk  from  which  it 
springs,  but  the  collective  capacity  of  all  the  branches  into 
which  an  artery  divides  is  greater  than  the  parent  vessel.  Since 
the  area  of  the  arterial  system  increases  as  its  vessels  divide,  it 
is  evident  that  the  collective  capacity  of  the  smaller  vessels 
and  capillaries  must  be  greater  than  the  collective  capacity  of 
the  trunks  from  which  they  arise.  As  the  same  rule  applies  to 
the  veins,  it  follows  that  the  arterial  and  venous  systems  may 
be  represented,  as  regards  capacity,  by  two  blunt  cones  whose 
apices  are  at  the  heart,  and  whose  bases  are  united  in  the  cap- 
illary system.  The  effect  of  this  arrangement  of  the  circulatory 
vessels  is  to  make  the  blood  flow  more  slowly  as  it  passes 
through  the  more  widely  distributed  vessels,  and  to  accelerate 

93 


94  ANATOMY   FOK   NUKSES.  [CHAP.  IX. 

its  speed  in  the  larger  and  less  numerous  trunks,  just  as  a  river 
flows  more  rapidly  through  its  narrow  and  deep  channels,  and 
lingers  in  those  that  are  broad  and  shallow. 

The  arteries  unite  at  frequent  intervals  when  they  are  said  to 
anastomose  or  inosculate.  Such  inosculations  admit  of  free 
communication  between  the  currents  of  the  blood,  tend  to  pro- 
mote equality  of  distribution  and  of  pressure,  and  to  obviate 
the  effects  of  local  interruption. 

Arteries  commonly  pursue  a  tolerably  straight  course,  but  in 
some  parts  of  the  body  they  are  tortuous.  They  often  become 
markedly  tortuous  in  old  persons  as  the  walls  of  the  arteries 
increase  in  length  and  size. 

In  describing  the  distribution  of  the  arteries  we  shall  first 
consider  the  artery  arising  from  the  left  ventricle  of  the  heart, 
the  aorta,  and  its  branches. 

The  aorta.  —  The  aorta  is  the  main  trunk  of  the  arterial  sys- 
tem. Springing  from  the  left  ventricle  of  the  heart,  it  arches 
over  the  root  of  the  left  lung,  descends  along  the  vertebral  col- 
umn, and  after  passing  through  the  diaphragm  into  the  abdomi- 
nal cavity,  ends  opposite  the  fourth  lumbar  vertebra  by  dividing 
into  the  right  and  left  common  iliac  arteries.  In  this  course 
the  aorta  forms  a  continuous  single  trunk,  which  gradually 
diminishes  in  size  from  its  commencement  to  its  termination 
(from  28  to  17  mm.),  and  gives  off  larger  or  smaller  branches 
at  various  points.  It  may  be  divided  into  the  ascending  aorta, 
the  short  part  which  is  contained  in  the  pericardium  ;  the  arch, 
the  part  extending  from  the  ascending  aorta,  and  forming  a 
well-marked  curve  in  front  of  the  trachea,  and  around  the  root 
of  the  left  lung  to  the  border  of  the  fourth  dorsal  vertebra ; 
the  descending  thoracic  aorta,  the  comparatively  straight  part 
extending  to  the  diaphragm;  the  abdominal  aorta,  below  the 
diaphragm.  The  ascending  aorta  gives  off  two  small  branches, 
the  right  and  left  coronary  arteries,  which  supply  the  substance 
of  the  heart  with  blood.  The  arch  gives  off  three  large  trunks, 
the  innominate,  the  left  common  carotid,  and  the  left  subclavian 
artery. 

The  innominate  artery  arises  from  the  right  upper  surface  of 
the  arch,  ascends  obliquely  towards  the  right,  until,  arriving  on 
a  level  with  the  upper  margin  of  the  clavicle,  it  divides  into  the 
right  common  carotid  and  right  subclavian  arteries.  Its  usual 
length  is  from  one  to  two  inches. 


CHAP.  IX.] 


THE   VASCULAR   SYSTEM. 


The  left  common  carotid  arises  from  the  middle  of  the  upper 
surface  of  the  arch  of  the  aorta,  and  the  left  subclavian  arises 
from  the  left  upper  surface  of  the  arch. 


B 


15 


10 


FIGS.  71,  72.  — THE  AORTA.  A,  from  before ;  B,  from  behind,  with  the  origin  of  its 
principal  branches.  (R.  Quain.)  1,  2,  ascending  aorta ;  2,  3,  arch  of  aorta ;  4,  innomi- 
nate artery ;  5,  left  carotid  ;  0,  left  subclavian  ;  7,  7,  7,  intercostal  and  lumbar  arteries ; 
8,  8,  renal  arteries;  9,  9,  common  iliac  arteries;  10,  middle  sacral  arteries;  11,  one  of 
the  phrenic  arteries;  +,  coeliac  axis;  12, gastric;  13,  hepatic;  14,  splenic  artery;  15, 
superior  mesenteric  ;  16,  inferior  mesenteric  :  17,  17;  spermatic  or  ovarian  arteries. 


96 


ANATOMY  FOR  KUESES. 


[CHAP.  IX. 


The  common  carotid  arteries.  —  As  the  left  common  carotid 
arises  from  the  middle  of  the  upper  surface  of  the  arch  of  the 
aorta,  while  the  right  common  carotid  arises  at  the  division  of 
the  innominate,  the  left  carotid  is  an  inch  or  two  longer  than 
the  right.  They  ascend  obliquely  on  either  side  of  the  neck 


Fia.  73. — THE  CAROTID,  SUBCLAVIAN,  AND  AXILLARY  ARTERIES.  1,  common 
carotid  artery;  2,  internal  carotid;  3  and  18,  external  carotid;  8,  facial  artery;  22, 
subclavian  artery ;  28,  axillary  artery ;  33,  commencement  of  brachial  artery. 

until,  on  a  level  with  the  upper  border  of  the  thyroid  cartilage, 
"  Adam's  apple,"  they  divide  into  two  great  branches,  of  which 
one,  the  external  carotid,  is  distributed  to  the  superficial  parts  of 
the  head  and  face,  and  the  other,  the  internal  carotid,  to  the 
brain  and  eye.  At  the  root  of  the  neck  the  common  carotids 


CHAP.  IX.] 


THE  VASCULAR   SYSTEM. 


97 


are  separated  from  each  other  by  only  a  narrow  interval,  corre- 
sponding with  the  width  of  the  trachea;  but  as  they  ascend 
they  are  separated  by  a  much 
larger  interval,  corresponding  with 
the  breadth  of  the  larynx  and 
pharynx. 

The  external  carotid  has  eight 
branches,  which  are  distributed 
to  the  throat,  tongue,  face,  and 
walls  of  the  cranium. 

The  chief  branches  of  the  in- 
ternal carotid  are  the  ophthalmic 
and  cerebral  arteries.  A  remark- 
able anastomosis  exists  between 
the  cerebral  arteries  at  the  base  of 
the  brain.  The  arteries  are  joined 
in  such  a  manner  as  to  form  a 
complete  circle,  and  this  anasto- 
mosis, known  as  the  "  circle  of 
Willis,"  both  equalizes  the  circula- 
tion of  the  blood  in  the  brain,  and 
also  provides,  in  case  of  destruction 
of  one  of  the  arteries,  for  the  blood 
reaching  the  brain  through  the 
other  vessels. 

The  subclavian  arteries.  —  The 
right  subclavian  arises  at  the 
division  of  the  innominate,  and 
the  left  subclavian  from  the  arch 
of  the  aorta.  The  subclavian 
arteries  are  the  first  portions  of  a 
long  trunk  which  forms  the  main 
artery  of  the  upper  limb,  and  which 
is  artificially  divided  for  purposes 
of  description  into  three  parts;  OF  THB  ARTERIES  OF  THE  A  KM, 

viz.   the  subclavian,    axillary,   and   ^S^^SLSSMS^ 

bracMal   arteries.      The    Subclavian    artery;  6,  deep  palmar  arch;  8,  ulnar 

artery  passes  a  short  way  up  the    artery- 

thorax  into  the  neck,  and  then  turns  downwards  to  rest  on  the 

first  rib.    At  the  outer  border  of  the  first  rib  it  ceases  to  be  called 


FIG.  74.  —  DEEP  ANTERIOR  VIEW 


98  ANATOMY   FOE,   NUKSES.  [CHAP.  IX. 

subclavian,  and  is  continued  as  the  axillary.  It  gives  off  large 
branches  to  the  back,  chest,  and  neck. 

The  axillary  artery  passes  through  the  axilla,  lying  to  the 
inner  side  of  the  shoulder  joint  and  upper  part  of  the  arm.  It 
gives  off  branches  to  chest,  shoulder,  and  arm. 

The  brachial  artery  extends  from  the  axillary  space  to  just 
below  the  bend  of  the  elbow,  where  it  divides  into  the  ulnar  and 
radial  arteries.  It  may  be  readily  located,  lying  in  the  depres- 
sion along  the  inner  border  of  the  biceps  muscle.  Pressure 
made  at  this  point  on  the  artery,  from  before  backwards  against 
the  humerus,  will  control  the  blood  supply  to  the  arm. 

The  ulnar  artery,  the  larger  of  the  two  vessels  into  which  the 
brachial  divides,  extends  along  the  side  of  the  forearm  into 
the  palm  of  the  hand,  where  it  terminates  in  the  superficial 
palmar  arch. 

The  radial  artery  appears,  by  its  direction,  to  be  a  continua- 
tion of  the  brachial,  although  it  does  not  equal  the  ulnar  in  size. 
It  extends  along  the  front  of  the  forearm  as  far  as  the  lower 
end  of  the  radius,  below  which  it  turns  round  the  outer  border 
of  the  wrist,  descends  between  the  bones  of  the  thumb  and  fore- 
finger, and  passes  forward  into  the  palm  of  the  hand.  It  ter- 
minates in  the  deep  palmar  arch.  The  superficial  and  deep 
palmar  arches  supply  the  hand  with  blood. 

The  thoracic  aorta  extends  from  the  lower  border  of  the  fourth 
dorsal  vertebra,  on  the  left  side,  to  the  opening  in  the  diaphragm 
below  the  last  dorsal  vertebra,  and  has  a  length  of  from  S'even 
to  eight  inches.  The  branches,  derived  from  the  thoracic  aorta, 
are  numerous,  but  small.  They  are  distributed  to  the  walls  of 
the  thorax,  and  to  the  viscera  contained  within  it. 

The  abdominal  aorta  commences  about  the  lower  border  of  the 
last  dorsal  vertebra,  and  terminates  below  by  dividing  into  the 
two  common  iliac  arteries.  The  bifurcation  usually  takes  place 
about  half-way  down  the  body  of  the  fourth  lumbar  vertebra, 
which  corresponds  to  a  spot  on  the  front  of  the  abdomen, 
slightly  below  and  to  the  left  of  the  umbilicus.  Its  length  is 
about  five  inches. 

The  abdominal  aorta  gives  off  numerous  branches,  which  may 
be  divided  into  two  sets ;  viz.  those  which  supply  the  viscera, 
and  those  which  are  distributed  to  the  walls  of  the  abdomen. 
The  former  consists  of  the  creliac  axis,  the  superior  mesenteric, 


PLATE  V.  —  THE  ABDOMINAL  AORTA  AND  ITS  PRINCIPAL  BRANCHES.  (Tiede- 
mann.)  a,  ensiform  appendix;  b,  inferior  vena  cava  and  c,  oesophagus,  passing 
through  diaphragm;  /,/,  right  and  left  kidneys,  with  the  supra-renal  bodies;  g,  «/, 
ureters;  h,  urinary  bladder;  k,  rectum,  divided  near  its  upper  end.  1, 1,  abdominal 
aorta;  2,  2',  and  3,  3',  right  and  left  inferior  phrenic  arteries;  4,  coeliac  axis;  5, 
superior  mesenteric  artery ;  6,  6,  renal  arteries ;  7,  7,  spermatic  or  ovarian  arteries ; 
8,  inferior  mesenteric  artery;  10,  10,  common  iliac  arteries;  11,  placed  between 
external  and  internal  iliac  arteries. 

99 


100 


ANATOMY   FOR   NURSES. 


[CHAP.  IX. 


the  inferior  mesenteric,  the  supra-renal,  the  renal,  and  the  sper- 
matic or  ovarian  arteries,  while  in  the  latter  are  included  the 

phrenic,  the  lumbar,  and  the 
middle  sacral  arteries. 

The  coeliac  artery,  or  axis, 
is  a  short,  wide  vessel,  usually 
not  iribre  than  half  an  inch  in 
length,  which  arises  from  the 
front  of  the  aorta,  close  to  the 
opening  in  the  diaphragm.  It 
divides  into  three  branches; 
viz.  the  gastric,  which  supplies 
the  stomach  ;  the  hepatic, 
which  supplies  the  liver ;  and 
the  splenic,  which  supplies  the 
spleen,  and  in  part  the  stom- 
ach and  pancreas. 

The  superior  mesenteric  ar- 
tery arises  from  the  fore  part 
of  the  aorta,  a  little  below 
the  coeliac  axis.  It  supplies 
the  whole  of  the  small  intes- 
tine beyond  the  first  portion 
(the  duodenum)  close  to  the 
stomach,  and  half  of  the  large 
intestine. 

The  inferior  mesenteric  ar- 
tery arises  from  the  front  of 
the  aorta,  about  an  inch  and 
a  half  above  its  bifurcation, 
and  supplies  the  lower  half 
of  the  large  intestine.  Con- 
tinued under  the  name  of  the 
superior  hemorrhoidal  artery, 
FIG.  75.  — iLiACAXDFEMoRALABTBRiEs.it  also  supplies  the  rectum. 

The  renal  arteries  are  of 
large  size,  in  proportion  to 
the  bulk  of  the  organs  which  they  supply.  They  arise  from  the 
sides  of  the  aorta,  about  half  an  inch  below  the  superior  mesen- 
teric artery,  that  of  the  right  side  being  generally  a  little  lower 


2,  common  iliac  artery;  4,  external  iliac; 
femoral  artery 


CHAP.  IX.] 


THE   VASCULAR   SYSTEM. 


101 


down  than  that  of  the  left.  Each  is  directed  outwards,  so  as  to 
form  nearly  a  right  angle  with  the  aorta.  Before  reaching  the 
kidney,  each  artery  divides  into  four  or  five  branches. 

The  ovarian  arteries,  corresponding  to  the  spermatic  arteries  in 
the  male,  arise  close  together  from  the  front  of  the  aorta,  a  little 
below  the  renal  arteries.  They  supply  the  ovaries,  and,  joined 
to  the  uterine  artery,  —  a  branch 
of  the  internal  iliac,  —  also  assist 
in  supplying  the  uterus.  During 
pregnancy  the  ovarian  arteries 
become  considerably  enlarged. 

The  common  iliac  arteries,  com- 
mencing at  the  bifurcation  of  the 
aorta,  pass  downwards  and  out- 
wards for  about  two  inches,  and 
then  divide  into  the  internal  and 
external  iliac  arteries. 

The  internal  iliac  artery  (hypo- 
gastric)  supplies  branches  to  the 
walls  and  viscera  of  the  pelvis. 

The  external  iliac  artery  forms 
a  large  continuous  trunk,  which 
extends  downwards  in  the  lower 
limb  to  just  below  the  knee :  it 
is  named  in  successive  parts  of  its 
course  external  iliac,  femoral,  and 
popliteal.  The  external  iliac  is 
placed  within  the  abdomen,  and 
extends  from  the  bifurcation  of  the 
common  iliac  to  the  lower  border  of 
Poupart's  ligament,  where  it  enters 
the  thigh  and  is  named  femoral.  FIG.  76.  —  VIEW  OF  POPLITEAL 

rr,,         .  .  , .         .         ,        ARTERY.    A,  biceps  muscle;   D,  D, 

Ine    femoral    artery    lies    in    the    gastrocnemius  ;    /,  popliteal  artery. 

upper  three-fourths  of  the   thigh, 

its  limits  being  marked  above  by  Poupart's  ligament,  and  below 
by  the  opening  in  the  great  adductor  muscle,  after  passing 
through  which  the  artery  receives  the  name  of  popliteal.  In 
the  first  part  of  its  course  the  artery  lies  along  the  middle  of 
the  depression  on  the  inner  aspect  of  the  thigh,  known  as 
Scarpa's  triangle.  In  this  situation  the  beating  of  the  artery 


102 


ANATOMY  FOR   NURSES. 


[ClIAP.   IX. 


may  be  felt,  and  the  circulation  through  the  vessel  may  be  most 
easily  controlled  by  pressure. 

The  popliteal  artery, 
continuous  with  the  fem- 
oral, is  placed  at  the  back 
of  the  knee  ;  just  below 
the  knee  joint  it  divides 
into  the  anterior  and 
posterior  tibial  arteries. 

The  posterior  tibial  ar- 
tery lies  along  the  back 
of  the  leg,  and  extends 
from  the  bifurcation  of 
the  popliteal  to  the 
ankle,  where  it  divides 
into  the  internal  and 
external  plantar  arteries. 

About  an  inch  below 
the  bifurcation  of  the 
popliteal,  the  posterior 
tibial  gives  off  a  large 
branch,  the  peroneal  ar- 
tery. 

The  anterior  tibial  ar- 
tery, the  smaller  of  the 
two  divisions  of  the 
popliteal  trunk,  extends 
along  the  front  of  the 
leg  to  the  bend  of  the 
ankle,  whence  it  is  pro- 
longed into  the  foot 
under  the  name  of  the 
dorsal  artery.  This 
FIG.  77.  — DEEP  VIEW  OF  unites  with  the  external 

THE  ARTERIES  OF  THE  BACK    an(J    jnternal    plantar    ar-        FIG.  78. -ANTERIOR 

OF  THE  LEG.      1,   popliteal  ARTERIFS   OF  THK 

artery ;  6,  division  of  pop-  tenes  to  form  the  plan-  4   anterior  tj 

liteal  into  anterior  and  pos-  t  h      hi  h  supplies  dorsal  artery, 

tenor  tibial  arteries ;  H,  pos- 
terior tibial ;  9,  peroneal.        blood  to  the  f OOt.1 

1  Outlining  the  aorta  and  its  branches  as  an  arterial  tree  will  greatly  aid  the 
student  in  mastering  the  arterial  distribution.  Also  colouring  the  arteries  red  in  the 
figures  would  serve  to  make  their  position  clearer  and  more  easily  remembered. 


VIEW 
THF:  LEG. 
artery ;  9, 


CHAP.  IX.] 


THE   VASCULAR   SYSTEM. 


103 


Venous  return.  —  The  arteries  begin  as  large  trunks,  which 
gradually  become  smaller  and  smaller  until  they  end  in  the 
small  capillary  tubes,  while  the  veins  begin  as  small  branches 
which  at  first  are  scarcely  distinguishable  from  the  capillaries. 
These  small  branches,  receiving  the  blood  from  the  capillaries 
throughout  the  body,  unite  to  form 
larger  vessels,  and  end  at  last  by 
pouring  their  contents  into  the 
right  auricle  of  the  heart  through 
two  large  trunks,  the  superior  vena 
cava  and  the  inferior  vena  cava. 
The  veins,  however,  which  bring 
back  the  blood  from  the  stomach, 
intestines,  spleen,  and  pancreas, 
do  not  take  the  blood  directly  to 
the  heart,  but  first  join  to  form 
a  large  trunk,  —  the  portal  vein, 
—  and  carry  this  blood  to  the 
liver.  When  the  portal  vein  enters 
the  liver,  it  breaks  up  into  cap- 
illaries, which,  after  branching 
throughout  the  liver  substance, 
unite  to  form  the  hepatic  veins: 
by  them  the  blood  is  conveyed 
into  the  inferior  vena  cava.  This 
constitutes  what  is  called  the 
portal  circulation,  and  is  the  only 
example  in  the  body  of  a  vein 
breaking  up  into  capillaries. 

The  veins  consist  of  a  super- 
ficial and  a  deep  set,  the  former 
running  immediately  beneath  the 
skin  and  hence  named  subcuta- 
neous,  the  latter  usually  aocom- 
panying  the  arteries  and  named 
venoB  comites.  These  two  sets  of  veins  have  very  frequent  com- 
munications with  each  other,  and  the  anastomoses  of  veins 
are  always  more  numerous  than  those  of  arteries. 

The  systemic  veins  —  that  is,  all  the  veins  of  the  body  with 
the  exception  of  the  pulmonary  and  portal  veins  —  are  naturally 
divided  into  two  groups. 


FIG.  79.  —  ARTERIES  OF  THE  FOOT. 
<;,   7,  8, 


104 


ANATOMY  FOE,  NURSES. 


[CHAP.  IX. 


I.  Those  from  which  the  blood  is  carried  to  the  heart  by  the 
superior  vena  cava,  viz.  the  veins  of  the  head  and  neck  and 

upper  limbs,  together  with  those  of 
the  spine  and  a  part  of  the  walls  of 
the  thorax  and  abdomen.  In  this 
group  we  may  include  the  veins  of 
the  heart,  which,  however,  pass  directly 
into  the  right  auricle  without  entering 
the  superior  vejia  cava. 

II.  Those  from  which  the  blood  is 
carried  to  the  heart  by  the  inferior  vena 
cava ;  viz.  the  veins  of  the  lower  limbs, 
the  lower  part  of  the  trunk,  and  the 
abdominal  viscera. 

1.  The  blood  returning  from  the 
head  and  neck  flows  on  each  side  into 
two  principal  veins,  the  external  and 
internal  jugular. 

The  external  jugular  commences  near 
the  angle  of  the  jaw  by  the  union  of 
two  smaller  veins,  and  descends  almost 
vertically  in  the  neck  to  its  termination 
in  the  subclavian  vein. 

The  internal  jugular,  receiving  the 
blood  from  the  cranial  cavity,  descends 
the  neck  close  to  the  outer  side  of  the 
internal  and  common  carotid  arteries. 
It  unites  at  a  right  angle  with  the 
subclavian  to  form  the  innominate  vein.1 

The  blood  from  the  upper  limbs  is 
returned  by  a  superficial  and  deep  set 
of  veins.  The  superficial  are  much 
larger  than  the  deep,  and  take  a  greater 


Fio.  80.  —  SKETCH  OF  THE 
PRINCIPAL  VENOUS  TRUNKS. 
1,  superior  vena  cava;  2,  in- 


1  NOTE  ON  VENOUS  CIRCULATION  OF  THE 
SKULL. — The  blood  from  the  skull  is  returned 
ferior  vena  cava;  3,  right  sub-  from  the  smaller  veins  to  the  internal  jugular 
clavian  and  innominate  veins;  veins  b  channelg  wh-  h  are  ^  ,  . 

4,  left  subclavian   and  mnomi-    . 

nate  veins  ;  5,  5,  right  and  left    but  smuses-     These  sinuses  are  spaces  left  be- 
internal  jugular  veins ;  8,  right    tween  the  layers  of  the  dura  mater,  and  are  lined 
azygos   vein ;    10,    left    azygos    by  a  continuation  of  the  lining  membrane  of  the 
vein ;  13, 13,  common  iliac  veins ;     veins. 
14, 14,  sacral  veins. 


CHAP.  IX.] 


THE   VASCULAR   SYSTEM. 


105 


share  in  returning  the  blood,  especially  from  the  distal  portion 
of  the  limb.  The  deep  veins  accompany  the  arteries,  and  are 
called  by  the  same  names.  Both 
sets  are  provided  with  valves,  and 
terminate  in  the  subclavian  vein. 

The  blood  from  the  spine,  walls 
of  thorax,  and  abdomen  is  chiefly 
returned  by  the  right  and  left  azygos 
veins,  which  are  longitudinal  vessels 
resting  against  the  thoracic  portion 
of  the  spinal  column.  They  com- 
municate below  with  the  inferior 
vena  cava,  and  terminate  above  in  the 
superior  vena  cava :  they  thus  form  a 
supplementary  channel  by  which  blood 
can  be  conveyed  from  the  lower  part 
of  the  body  to  the  heart  in  case  of 
obstruction  in  the  inferior  vena  cava. 

The  innominate  veins,  commencing 
on  each  side  by  the  union  of  the  sub- 
clavian and  internal  jugular,  behind 
the  inner  end  of  the  clavicle,  transmit 
the  blood  returning  from  the  head 
and  neck,  the  upper  limbs,  and  a 
part  of  the  thoracic  wall ;  they  end 
below  by  uniting  to  form  the  superior 
vena  cava.  Both  innominate  veins 
are  joined  by  many  side  tributaries : 
they  also  receive,  at  the  junction  of 
the  subclavian  and  internal  jugular, 
the  lymph ;  on  the  left  side  from  the 
thoracic  duct,  and  on  the  right  from 
the  right  lymphatic  duct. 

The  superior  or  descending  vena  cava 

is  formed  by  the  union  of  the  right  OF  LoWEB  EXTREMITY.— i,  veins 
and  left  innominate  veins.   It  is  about  of  the  foot;  2  internal  ~&*™£ 

,        vein  ;  3,  superficial  veins  of  calf ; 

three  inches  long,  and  opens  into  the  4>  superficial  veins  of  thigh, 
right  auricle,  opposite  the  third  rib. 

The  blood  from  the  lower  limbs  is  also  returned  by  a  super- 
ficial and  deep  set  of  veins.     They  are  more  abundantly  supplied 


_  S(JPEEFICIAL 


106  ANATOMY   FOE   NURSES.  [CHAP.  IX. 

with  valves  than  the  veins  of  the  upper  limbs.  The  deep  veins 
accompany  the  arteries.  The  two  largest  superficial  veins  are 
the  internal  or  long  saphenous,  and  the  external  or  short  saphenous 
vein.  The  internal  saphenous  extends  from  the  ankle  to  within 
an  inch  and  a  half  of  Poupart's  ligament.  It  lies  along  the 
inner  side  of  the  leg  and  thigh,  and  terminates  in  the  femoral 
vein.  The  external  saphenous  arises  from  the  sole  of  the  foot, 
and,  passing  up  the  back  of  the  leg,  ends  in  the  deep  popliteal. 

Both  deep  and  superficial  veins  pour  their  contents  into  the 
external  iliac.  The  blood  is  returned  from  the  pelvis  by  the 
internal  iliac  veins,  which,  uniting  with  the  external  iliac,  form 
the  two  common  iliac  veins.  Extending  from  the  base  of  the 
sacrum  to  the  fourth  lumbar  vertebra,  the  two  common  iliacs 
unite  to  form  the  inferior  vena  cava. 

The  inferior  or  ascending  vena  cava  returns  the  blood  from 
the  lower  limbs,  pelvis,  and  abdomen.  It  begins  at  the  junction 
of  the  two  common  iliacs,  and  thence  ascends  along  the  right 
side  of  the  aorta,  perforates  the  diaphragm,  and  terminates  by 
entering  the  right  auricle  of  the  heart.  The  inferior  vena  cava 
receives  many  tributaries,  the  chief  of  which  are  the  lumbar, 
ovarian,  renal,  and  hepatic  veins. 

The  pulmonary  artery.  —  The  pulmonary  artery  conveys  the 
dark  blood  from  the  right  side  of  the  heart  to  the  lungs.  The 
main  trunk  is  a  short,  wide  vessel  (diameter  30  mm.)  which 
arises  from  the  right  ventricle  and  runs  for  a  distance  of  two 
inches  backwards  and  upwards  (vide  fig.  63).  Between  the 
fifth  and  sixth  dorsal  vertebrae,  it  divides  into  two  branches, 
—  the  right  and  left  pulmonary  arteries,  —  which  pass  to  the 
right  and  left  lungs. 

The  pulmonary  veins.  —  The  pulmonary  veins  are  four  short 
trunks  which  convey  the  red  blood  from  the  lungs  to  the  left 
side  of  the  heart,  and  which  are  found  —  two  on  each  side  —  in 
the  root  of  the  corresponding  lung.  The  pulmonary  veins  have 
no  valves. 


CHAP.  IX.] 


THE   VASCULAR   SYSTEM. 


107 


PLAN  OF   ARTERIAL   DISTRIBUTION. 


I. 

Arch  of  Aorta 


II. 

Thoracic 

Aorta 


III. 

Abdominal 
Aorta 


R.  and  L.  coronary. 

C  R.  c.  carotid. 
Innominate  j  R.  subclavian  —  ax- 

l     illary  —  brachial. 
L.  c.  carotid. 
L.  subclavian. 

r  Intercostal. 
J  Pericardial. 
I  Bronchial. 
I  (Esophageal. 

r  Gastric. 
Coeliac  axis     -I  Hepatic. 

I  Splenic. 
Sup.  mesenteric. 
Inf.  mesenteric. 
Renal. 
Ovarian. 
Phrenic. 
Lumbar. 
.  Sacral. 


(  Superficial 
Ulnar  \      palmar 

I     arch. 

rDeep 
Radial        paimer 

arch, 


Common  Iliac 
arteries. 


r  _,        , .,  .  ,    f  Ext.  plantar  i  ™ 

«,..,.  ,          Post,  tibial  \  T  ,  Plantar 

Ext.  iliac  —  fern-  \  [  Int.  plantar  V         ^ 


oral  —  popliteal  I  Ant.  tibial,  dorsal. 
I  Int.  iliac. 


arch. 


PLAN  OF  VENOUS   RETURN. 


The  veins  from  the 
head,  face,  and  neck 
unite  to  form 

The  deep-seated  and  l  R.  ,ht  &  d  The  internal  ju- 
superficial  veins  ^  ^  gular  unites 
from  the  upper  with  the  sub- 

limbs  unite  to  form  J  clavians      to 

form 


3  1  External  (the  external  jugular  terminates  in  sub- 
clavian veins)  and  internal  jugular  veins. 


Right         1  _ 

, ,  ,.     SUP. 
and  left 

.     }       VE! 

mnomi- 

CAVA. 


nate 


The  deep-seated  and 

superficial        veins    External 
from      the      lower         iliacs 
limbs  unite  to  form 

The  veins  from  pelvis  ]  Internal 
unite  to  form  f      iliacs 


Right  and  left     1  INFERIOR  VENA 
common  iliacs  J      CAVA. 


108  ANATOMY  FOR  NURSES.  [CHAP.  IX. 

The  right  and  left  azygos  veins  connected  with  the  inferior  vena  cava 
below,  and  superior  vena  cava  above,  form  a  supplementary  channel. 

The  veins  from  stomach,  spleen,  pancreas,  and  intestines  unite  to  form 
the  portal  vein,  which  breaks  up  into  capillaries  in  the  liver,  and  is  returned 
to  the  inferior  vena  cava  by  the  hepatic  veins. 


CHAPTER  X. 


THE  VASCULAR  SYSTEM  CONTINUED:  THE  GENERAL  CIRCULA- 
TION; THE  PULSE  AND  ARTERIAL  PRESSURE;  VARIATIONS 
IN  THE  CAPILLARY  CIRCULATION. 

The  general  circulation  of  the  blood.  —  At  each  beat  of  the 
heart  the  contraction  of  the  ventricles  drives  a  certain  quantity 
of  blood,  probably  amounting  to  four 
ounces,  with  great  force  into  the 
aorta  and  pulmonary  artery.  The 
aorta  delivers  this  supply  of  blood 
from  the  left  ventricle,  through  its 
branches,  to  the  capillaries  in  all 
parts  of  the  body,  except  the  lungs. 
In  the  capillaries,  the  blood  is  robbed 
of  oxygen  and  other  constituents 
necessary  for  the  life  and  growth 
of  the  tissues,  is  loaded  with  car- 
bonic acid  and  other  waste  matters, 
and  is  returned  by  the  superior  and 
inferior  venae  cavse  to  the  right  side 
of  the  heart.  From  the  right  side 
of  the  heart,  the  blood  is  conveyed 
by  the  pulmonary  artery  to  the 
capillaries  in  the  lungs,  where  it 
receives  a  fresh  supply  of  oxygen 

and  gives  Up  the  carbonic  acid  with    LATION.    A,  aorta;  P,  pulmonary 

.       i     T     i      •          artery;    0,  O,  auricles;   V,  V,  ven- 

which  it  has  become  loaded  during    tricles  •  /  /,  intestines ;  F,  liver ; 

its   circulation   through    the   body.  l£™?^'%?£*™ 

Thus    a    double    circulation    is    COn-    hepatic  veins  ;  6,  portal  vein ;  7,  8, 

stantly   and    simultaneously   going 
on,  the  artery  from  the  left  side  of  veins. 

109 


FIG.  82.  — DIAGRAM  OF  CIRCU- 


110  ANATOMY   FOR   NURSES.  [CHAP.  X. 

the  heart  sending  the  pure  oxygenated  blood  to  the  general 
system,  and  the  artery  from  the  right  side  of  the  heart  sending 
the  impure  blood  to  the  lungs  for  purification.  The  more  ex- 
tensive circulation  is  usually  called  the  general  or  systemic 
circulation,  while  the  lesser  circulation  is  generally  known  as 
the  pulmonary. 

Some  features  of  the  arterial  circulation.  —  The  flow  of  blood 
into  the  arteries  is  most  distinctly  intermittent ;  sudden,  rapid 
discharges  alternating  with  relatively  long  intervals  during 
which  the  arteries  receive  no  blood  from  the  heart.  Every 
time  the  heart  beats  just  as  much  blood  flows  from  the  veins 
into  the  right  auricle  as  escapes  from  the  left  ventricle  into  the 
aorta,  but  this  inflow  is  much  slower  and  takes  a  longer  time 
than  the  discharge  from  the  ventricles. 

The  pulse.  —  When  the  finger  is  placed  on  an  artery  a  sense 
of  resistance  is  felt,  and  this  resistance  seems  to  be  increased  at 
intervals,  corresponding  to  the  heart-beat,  the  artery  at  each 
heart-beat  being  felt  to  rise  up  or  expand  under  the  finger. 
This  constitutes  the  pulse ;  and,  in  certain  arteries  which  lie 
near  the  surface,  this  pulse  may  be  seen  with  the  eye.  When 
the  finger  is  placed  on  a  vein  very  little  resistance  is  felt ;  and, 
under  ordinary  circumstances,  no  pulse  can  be  perceived  by  the 
touch  or  by  the  eye. 

As  each  expansion  of  an  artery  is  produced  by  a  contraction 
of  the  heart,  the  pulse,  as  felt  in  any  superficial  artery,  is  a 
convenient  guide  for  ascertaining  the  character  of  the  heart's 
action.  The  radial  artery  at  the  wrist,  owing  to  its  accessible 
situation,  is  usually  employed  for  this  purpose.  Any  variation 
in  the  frequency,  force,  or  regularity  of  the  heart's  action  is 
indicated  by  a  corresponding  modification  of  the  pulse  at 
the  wrist. 

The  average  frequency  of  the  pulse  in  man  is  seventy-two 
beats  per  minute.  This  rate  may  be  increased  by  muscular 
action.  Even  the  variation  of  muscular  effort  entailed  between 
the  standing,  sitting,  and  recumbent  positions  will  make  a 
difference  in  the  frequency  of  the  pulse  of  from  eight  to  ten 
beats  per  minute.  Age  has  a  marked  influence  in  the  same 
direction.  According  to  Carpenter,  the  pulse  of  the  foetus  is 
about  140,  and  that  of  the  newly  born  infant  130.  During  the 
first,  second,  and  third  years,  it  gradually  falls  to  100 ;  by  the 


CHAP.  X.]  THE   VASCULAR   SYSTEM.  Ill 

fourteenth  year  to  80 ;  and  is  reduced  to  the  adult  standard  by 
the  twenty-first  year.  At  every  age,  mental  excitement  may 
produce  a  temporary  acceleration,  varying  in  degree  with  the 
^peculiarities  of  the  individual. 

As  a  rule,  the  rapidity  of  the  heart's  action  is  in  inverse  ratio 
to  its  force.  A  slow  pulse,  within  physiological  limits,  is 
usually  a  strong  one,  and  a  rapid  pulse  comparatively  feeble. 
The  same  is  true  in  disturbance  of  the  heart's  action  in  disease ; 
the  pulse  in  fever,  or  other  debilitating  affections,  becoming 
weaker  as  it  grows  more  rapid. 

Arterial  tension.  —  When  an  artery  is  severed,  the  flow  of 
blood  from  the  proximal  end  (that  on  the  heart  side)  comes  in 
jets  corresponding  to  the  heart-beats,  though  the  flow  does  not 
cease  between  the  beats.  The  larger  the  artery,  and  the  nearer 
to  the  heart,  the  greater  the  force  with  which  the  blood  issues, 
and  the  more  marked  the  intermittence  of  the  flow. 

When  a  corresponding  vein  is  severed,  the  flow  of  blood, 
which  is  chiefly  from  the  distal  end  (that  away  from  the  heart), 
is  not  intermittent,  but  continuous ;  the  blood  comes  out  with 
comparatively  little  force,  and  "  wells  up,"  rather  than  "  spurts 
out." 

The  continuous,  uninterrupted  flow  of  blood  in  the  veins  is 
caused  by  the  elasticity  of  the  arterial  walls.  On  account  of  the 
small  size  of  the  capillaries  and  small  arteries  the  blood  meets  with 
a  great  deal  of  resistance  in  passing  through  them;  and,  in  conse- 
quence, the  blood  cannot  get  through  the  capillaries  into  the  veins 
so  rapidly  as  it  is  thrown  into  the  arteries  by  the  heart.  The 
whole  arterial  system,  therefore,  becomes  over-distended  with 
blood,  and  the  greater  the  resistance,  the  greater  the  -pressure 
on,  and  distension  of,  the  arterial  walls.  The  following  illus- 
tration will  explain  how  the  elasticity  of  the  arteries  enables 
them  to  deliver  the  blood  in  a  steady  flow  to  the  veins  through 
the  capillaries. 

If  a  syringe  be  fastened  to  one  end  of  a  long  piece  of  elastic 
tubing,  and  water  be  pumped  through  the  tubing,  it  will  flow 
from  the  far  end  in  jerks.  But  if  we  stuff  a  piece  of  sponge 
into  this  end  of  the  tubing,  or  offer  in  any  way  resistance  to 
the  outflow  of  the  water,  the  tubing  will  distend,  its  elasticity 
be  brought  into  play,  and  the  water  flow  from  the  end  not  in 
jerks,  but  in  a  stream,  which  is  more  and  more  completely  con- 
tinuous the  longer  and  more  elastic  the  tubing. 


112  ANATOMY  FOR  NURSES.  [CHAP.  X. 

Substitute  for  the  syringe  the  heart,  for  the  sponge  the  cap- 
illaries and  small  arteries,  for  the  tubing  the  whole  arterial  sys- 
tem, and  we  have  exactly  the  same  result  in  the  living  body. 
Through  the  action  of  the  elastic  arterial  walls  the  separate  jets 
from  the  heart  are  blended  into  one  continuous  stream.  The 
whole  force  of  each  contraction  of  the  heart  is  not  at  once 
spent  in  driving  a  quantity  of  blood  out  of  the  capillaries ;  a 
part  only  is  thus  spent,  the  rest  goes  to  distend  the  elastic 
arteries.  But  during  the  interval  between  that  beat  and  the 
next  the  distended  arteries  are  narrowing  again,  by  virtue  of 
their  elasticity,  and  so  are  pressing  the  blood  on  in  a  steady 
stream  into  the  capillaries  with  as  much  force  as  they  were 
themselves  distended  by  the  contraction  of  the  heart. 

The  degree  of  tension  to  which  the  arterial  walls  are  sub- 
jected depends  upon  the  force  of  the  heart-beat,  and  upon  the 
resistance  offered  by  the  smaller  arteries,  the  normal  general 
blood  pressure  being  mainly  regulated  by  the  "  tone "  of  the 
minute  arteries. 

Variations  in  the  capillary  circulation.  —  Most  of  the  changes 
in  the  capillary  circulation  are  likewise  dependent  upon  the 
condition  of  the  smaller  arteries.  When  under  certain  nervous 
influences  they  contract,  the  blood  supply  to  the  capillaries  is 
greatly  lessened ;  when,  on  the  other  hand,  they  dilate,  the 
blood  supply  is  greatly  increased.  The  phenomena  produced 
by  these  local  variations  in  the  blood  supply  of  certain  parts  are 
very  familiar  to  us ;  the  redness  of  skin  produced  by  an  irritat- 
ing application,  the  blushing  or  paling  of  the  face  from  mental 
emotion,  the  increased  flow  of  blood  to  the  mucous  membranes 
during  digestion,  being  all  instances  of  this  kind. 

But  the  condition  of  the  capillary  walls  themselves  also 
exerts  an  influence  upon  the  capillary  circulation.  If  some 
transparent  tissue,  preferably  the  web  of  a  frog's  foot,  be  watched 
under  the  microscope,  it  will  be  observed  that  in  the  small 
capillaries  the  corpuscles  are  pressed  through  the  channel  in 
single  file,  each  corpuscle  as  it  passes  occupying  the  whole  bore 
of  the  capillary.  In  the  larger  capillaries  and  smaller  arteries 
and  veins  the  red  corpuscles  run  in  the  middle  of  the  channel, 
forming  a  coloured  core,  between  which  and  the  sides  of  the 
vessels  is  a  colourless  layer  containing  no  red  corpuscles,  and 
called  the  "peripheral  zone."  In  the  peripheral  zone  are  fre- 


CHAP.  X.]  THE   VASCULAR   SYSTEM.  113 

quently  seen  white  corpuscles,  sometimes  clinging  to  the  walls 
of  the  vessel,  sometimes  rolling  slowly  along,  and  in  general 
moving  irregularly,  stopping  awhile,  and  then  suddenly  moving 
on  again. 

These  are  the  phenomena  of  the  normal  circulation,  but  a 
different  state  of  things  sets  in  when  the  condition  of  the  blood- 
vessels is  altered  in  inflammation.1  If  an  irritant,  such  as  a 
drop  of  chloroform,  be  applied  to  the  portion  of  transparent 
tissue  under  observation,  the  following  changes  may  be  seen  to 
occur:  the  arteries  dilate,  the  blood  flows  in  greater  quantity 
and  with  more  rapidity,  the  capillaries  become  filled  with  cor- 
puscles, and  the  veins  appear  enlarged  and  full.  This  condition 
of  distension  may  pass  away,  and  the  blood-vessels  return  to 
their  normal  state,  the  effect  of  the  irritant  having  merely  pro- 
duced a  temporary  redness. 

The  irritant,  however,  usually  produces  a  more  decided 
change.  The  white  corpuscles  begin  to  gather  in  the  periph- 
eral zones,  and  this  takes  place  though  the  vessels  still 
remain  dilated  and  the  stream  of  blood  still  continues  rapid, 
though  not  so  rapid  as  at  first.  Each  white  corpuscle  exhibits 
a  tendency  to  stick  to  the  sides  of  the  vessels,  and,  driven  away 
from  the  arteries  by  the  stronger  arterial  current,  becomes 
lodged  in  the  veins.  Since  white  corpuscles  are  continually 
arriving  on  the  scene,  the  inner  surface  of  the  veins  and  cap- 
illaries soon  become  lined  with  a  layer  of  these  cells.  Now, 
though  the  vessels  still  remain  dilated,  the  stream  of  blood 
begins  to  slacken,  and  the  white  corpuscles  lying  in  contact 
with  the  walls  of  the  vessels  are  seen  to  thrust  themselves 
through  the  distended  walls  into  the  lymph  spaces  outside. 
This  migration  of  the  white  cells  is  accomplished  by  means  of 
their  amoeboid  movements.  They  thrust  elongated  processes 
through  the  walls,  and  then,  as  these  processes  increase  in  size, 
the  body  of  the  cell  passes  through  into  the  enlarged  process 
beyond,  the  perforation  appearing  to  take  place  in  the  cement 
substance  between  the  pavement  epithelial  cells  forming  the 
walls  of  the  vessels.  Through  this  migration,  the  lymph 
spaces  around  the  vessels  in  the  inflamed  area  become  crowded 

1  The  following  account  of  the  changes  occurring  in  inflammation  does  not 
strictly  belong  to  a  text-book  on  physiology,  but  I  have  ventured  to  introduce  it, 
as  especially  interesting  to  nurses,  out  of  "  Foster's  Physiology." 


114  ANATOMY   FOR  NUKSES.  [CHAP.  X. 

with  white  corpuscles.  At  the  same  time  the  lymph  not  only 
increases  in  amount,  but  changes  somewhat  in  its  chemical 
characters ;  it  becomes  more  distinctly  and  readily  coagulable, 
and  is  sometimes  spoken  of  as  "  exudation  fluid."  This  change 
of  the  lymph  with  the  increased  quantity,  together  with  the 
dilated  crowded  condition  of  the  blood-vessels,  gives  rise  to  the 
swelling  which  is  one  of  the  features  of  inflammation. 

If  the  inflammation  now  passes  away,  the  white  corpuscles 
cease  to  emigrate,  cease  to  stick  so  steadily  to  the  sides  of  the 
vessels,  the  stream  of  blood  quickens  again,  the  vessels  regain 
their  ordinary  calibre,  and  a  normal  circulation  is  re-established. 
But  this  inflammatory  condition,  instead  of  passing  off,  may  go 
on  to  a  further  stage ;  and,  if  this  is  the  case,  more  and  more 
white  corpuscles,  arrested  in  their  passage,  crowd  and  block  the 
channels,  so  that,  though  the  vessels  remain  dilated,  the  stream 
becomes  slower  and  slower,  until  at  last  it  stops  altogether,  and 
stagnation  or  "  stasis  "  sets  in.  The  red  corpuscles,  in  this  con- 
dition of  things,  are  driven  in  among  the  white  corpuscles,  the 
vessels  are  filled  and  distended  with  a  mingled  mass  of  red  and 
white  corpuscles,  and  it  may  now  be  observed  that  the  red  cor- 
puscles also  begin  to  find  their  way  through  the  distended  and 
altered  walls  of  the  capillaries  into  the  lymph  spaces  outside. 
This  is  called  the  diapedesis  of  the  red  corpuscles. 

This  stagnation  stage  of  inflammation  may  be  the  beginning 
of  further  mischief  and  of  death  to  the  inflamed  tissue,  but  it, 
too,  may,  like  the  earlier  stages,  pass  away. 

General  summary  of  the  circulation.  —  The  perfect  circulation 
of  the  blood  is  dependent  upon  certain  factors,  the  chief  of 
which  are :  (1)  the  character  of  the  heart-beat ;  (2)  the  con- 
traction and  relaxation  of  the  minute  arteries ;  (3)  the  elas- 
ticity and  extensibility  of  the  arterial  walls ;  (4)  the  perfect 
adjustment  of  the  valves. 

The  character  of  the  heart-beat  is  mainly  determined  by  the 
condition  of  its  muscular  substance,  and  any  interference  with 
the  nutrition  of  the  heart  leading  to  degeneration  of  its  mus- 
cular walls  very  seriously  affects  the  heart's  action. 

The  contraction  and  relaxation  of  the  smaller  arteries  is 
under  the  influence  of  the  nervous  system,  the  particular  fibres 
distributed  to  them  being  known  as  the  vaso-motor  nerves. 
The  widening  and  narrowing  of  these  arteries  not  only  affects 


CHAP.  X.]  THE   VASCULAR   SYSTEM.  115 

the  local  circulation  in  different  parts  of  the  body,  but  the 
amount  of  resistance  they  oppose  to  the  arterial  impulse  also 
influences  in  some  degree  the  character  of  the  heart-beat. 

The  elasticity  and  extensibility  of  the  arteries  change  with 
the  age  of  the  individual.  As  we  grow  older  the  arterial  walls 
grow  stiffer  and  more  rigid,  a'nd  become  less  well  adapted  for 
the  unceasing  work  they  are  called  upon  to  perform.  The 
valves  also  show  signs  of  age  as  years  advance,  and  even  if  not 
injured  by  disease,  do  not  adjust  themselves  so  perfectly  as  in 
early  life. 

Still,  the  heart  has  a  marvellous  facility  for  adjusting  itself 
to  changed  conditions,  and  the  circulation  of  the  blood  may 
go  on  for  years  with  the  integrity  of  the  vascular  mechanism 
greatly  impaired. 

FOETAL  CIRCULATION.  —  The  peculiarities  of  the  foetal  circu- 
lation, leaving  details  aside,  are  —  the  direct  communication 
between  the  two  auricles  of  the  heart  through  an  opening 
called  the  foramen  ovale ;  the  communication  between  the  pul- 
monary artery  and  descending  portion  of  the  arch  of  the  aorta 
by  means  of  a  tube  called  the  ductus  arteriosus ;  and  the  com- 
munication between  the  placenta  and  the  foetus  by  means  of 
the  umbilical  cord. 

The  arterial  blood  for  the  nutrition  of  the  foetus  is  carried  from 
the  placenta  along  the  umbilical  cord  by  the  umbilical  vein. 
Entering  the  foetus  at  the  umbilicus  the  blood  passes  upwards 
to  the  liver  and  is  conveyed  into  the  inferior  vena  cava  in  two 
different  ways.  The  larger  quantity  first  enters  the  liver,  and 
alone,  or  in  conjunction  with  the  blood  from  the  portal  vein, 
ramifies  through  the  liver  before  entering  the  inferior  vena 
cava,  by  means  of  the  hepatic  veins.  The  smaller  quantity  of 
blood  passes  directly  from  the  umbilical  vein  into  the  inferior 
vena  cava,  by  a  tube  called  the  ductus  venosus. 

In  the  inferior  vena  cava  the  blood  from  the  placenta 
becomes  mixed  with  the  blood  returning  from  the  lower  ex- 
tremities of  the  foetus.  It  enters  the  right  auricle  and  guided 
by  a  valve,  the  Eustachian  valve,  passes  through  the  foramen 
ovale  into  the  left  auricle.  In  the  left  auricle  it  unites  with  a 
small  quantity  of  blood  returned  from  the  lungs  by  the  pul- 
monary veins.  From  the  left  auricle  the  blood  passes  into  the 
left  ventricle,  and  is  distributed  by  the  aorta  almost  entirely  to 


PLATE  VI.  —  PLAN  OF  F(ETAL  CIRCULATION.  In  this  plan,  the  figured  arrows  rep- 
resent the  kind  of  blood,  as  well  as  the  direction  which  it  takes  in  the  vessels.  Thus, 
arterial  blood  is  figured ;  venous  blood  —  — ;  mixed  (arterial  and  venous) 


116 


CHAP.  X.]  THE  VASCULAR   SYSTEM.  117 

the  upper  extremities.  Returned  from  the  upper  extremities 
by  the  superior  vena  cava  the  blood  enters  the  right  auricle 
and,  passing  over  the  Eustachian  valve,  descends  into  the  right 
ventricle,  and  from  the  right  ventricle  into  the  pulmonary 
artery.  As  the  lungs  in  the  foetus  are  solid,  they  require  very 
little  blood,  and  the  greater  part  of  the  blood  passes  through 
the  ductus  arteriosus  into  the  descending  aorta,  where,  mixing 
with  the  blood  delivered  to  the  aorta  by  the  left  ventricle,  it 
descends  to  supply  the  lower  extremities  of  the  foetus,  the  chief 
portion  of  this  blood,  however,  being  carried  back  to  the  pla- 
centa by  the  two  umbilical  arteries. 

From  this  description  of  the  foetal  circulation,  it  will  be 
seen  :  — 

1.  That  the  placenta  serves  the  double  purpose  of  a  respi- 
ratory and  nutritive  organ,  receiving  the  venous  blood  from 
the  foetus,  and  returning  it  again  charged  with  oxygen  and 
additional  nutritive  material. 

2.  That  the  greater  part  of   the  blood  traverses  the  liver 
before  entering  the  inferior  vena  cava ;  hence  the  large  size  of 
this  organ  at  birth. 

3.  That  the  blood  from  the  placenta  passes  almost  directly 
into  the  arch  of  the  aorta,  and  is  distributed  by  its  branches  to 
the   head   and   upper   extremities ;   hence   the   large   size    and 
perfect  development  of  those  parts  at  birth. 

4.  That  the  blood  in  the  descending  aorta  is  chiefly  derived 
from  that  which  has  already  circulated  in  the  upper  extremities, 
and,  mixed  with  only  a  small  quantity  from  the  left  ventricle, 
is  distributed  to  the  lower  extremities ;  hence  the  small  size  and 
imperfect  development  of  these  parts  at  birth. 

Development  of  blood-vessels  and  corpuscles.  —  The  blood-vessels  and 
red  corpuscles  are  formed  very  early  in  the  embryo.  They  are  developed  in 
that  portion  of  the  primitive  tissue  called  the  mesoblast.  The  cells  which 
are  to  form  the  vessels  become  extended  into  processes  of  varying  length, 
which  grow  out  from  the  cells  in  two  or  more  directions.  The  cells  become 
united  with  one  another,  either  directly  or  by  the  junction  of  their  processes, 
so  that  an  irregular  network  is  thus  formed.  Meanwhile  the  nuclei  in  the 
cells  multiply,  and  each  nucleus  surrounds  itself  with  a  small  amount  of 
cell  protoplasm .  The  corpuscles  thus  formed  acquire  a  reddish  colour,  and 
the  protoplasmic  network  in  which  they  lie  becomes  hollowed  out  into  a 
system  of  branched  canals  containing  fluid,  in  which  the  nucleated  coloured 
corpuscles  float.  The  protoplasmic  walls  of  the  vessels  gradually  change 


118 


ANATOMY   FOE   NUESES. 


[CHAP.  X. 


into  the  flattened  cells  which  compose  the  wall  of  the  capillaries,  and  which 
form  the  lining  membrane  of  the  arteries  and  veins.     The  remaining  coats 


P 

FIG.  83.  —  ISOLATED  CAPILLARY  NETWORK  FORMED  BY  THE  JUNCTION  OP 
SEVERAL  HOLLOWED-OUT  CELLS,  AND  CONTAINING  COLOURED  BLOOD-CORPUSCLES 
IN  A  CLEAR  FLUID,  p,  p,  pointed  cell-processes  extending  in  different  directions 
for  union  with  neighbouring  capillaries. 

of  the  larger  vessels  are  developed  later  from  other  cells  which  apply  them- 
selves to  the  exterior  of  these  tubes. 

The  first  white  corpuscles  do  not  appear  in  the  vessels  so  early  as  the 
coloured  ones.  They  probably  occur  in  the  beginning  as  free  cells  and 
wander  in  from  the  outside. 

The  new  vessels  which  form  in  the  healing  of  wounds  and  in  the  restora- 
tion of  lost  parts  are  produced  by  a  process  which  is  essentially  the  same  as 
above  described.  Blood-corpuscles,  however,  are  not  produced  within  them, 
and  it  is  still  a  matter  of  doubt  as  to  where  and  how  the  red  corpuscles 
originate  after  birth.  The  white  corpuscles  are  undoubtedly  produced  to  a 
large  extent  in  the  lymphatic  glands  and  other  lyrnphoid  structures. 


CHAPTER  XI. 

VASCULAR  SYSTEM  CONCLUDED:  LYMPHATIC  VESSELS  AND 
LYMPH.  LYMPHATIC  GLANDS  AND  BODIES  OF  ALLIED 
STRUCTURE. 

The  lymphatics.  —  In  addition  to  the  blood-vessels,  which  form 
a  continuous  series  of  tubes  for  the  passage  of  the  blood,  there 
is  another  system  of  vessels  in  the  body,  which  arise  in  the 
different  tissues,  and  pour  their  contents  into  the  great  veins 
near  the  heart.  The  fluid  which  these  vessels  contain  is  ab- 
sorbed from  the  tissues,  and  is  called,  from  its  transparent 
watery  appearance,  "  lymph  "  (lympha,  water),  while  the  ves- 
sels themselves  are  known  as  lymphatics  or  absorbents. 

The  absorbents  may  be  divided  into  two  sets:  the  lacteals, 
which  absorb  the  milk-like  fluid,  called  chyle,  from  the  intes- 
tines and  carry  it  to  the  thoracic  duct;  arfd  the  lymphatics 
proper,  which  take  up  the  lymph  from  all  parts  of  the  body  and 
return  it  to  the  blood  through  the  thoracic  and  right  lym- 
phatic ducts.  These  two  sets  of  vessels,  however,  are  alike  in 
structure,  and  will  be  considered  together  under  the  general 
name  of  lymphatics. 

The  lymphatics  are  found  in  nearly  all  the  tissues  that  are 
supplied  with  blood.  The  larger  trunks  usually  accompany  the 
deep-seated  blood-vessels,  and  the  smaller  vessels  form  networks 
in  all  parts  of  the  body  where  the  extensively  distributed  and 
penetrative  connective  tissue  is  found. 

The  lymphatics  have  their  origin  in  the  connective  tissue. 
They  may  be  said  to  begin  as  irregularly  shaped  or  tubular 
spaces  in  the  areolse,  and  are  distinguished  from  the  lymph 
spaces  in  the  tissue  outside  by  being  lined  with  a  single  layer  of 
flat,  transparent  epitheloid  cells  having  a  peculiar  dentated  out- 
line, by  means  of  which  they  are  readily  recognized.  These 

119 


120  ANATOMY   FOR  NURSES.  [CHAP.  XI. 

united  lymph  vessels  form  very  irregular  labyrinths,  communi- 
cate freely  with  one  another,  and  are  altogether  wider  than  the 
blood  capillaries.  They  form  the  link  between  the  lymph  in 


FIG.  84.  — A  SMALL  PORTION  OF  A  LYMPHATIC  PLEXUS.  Magnified  110  diam- 
eters. (Ranvier.)  L,  lymphatic  vessel  with  characteristic  epithelium;  C,  cell 
spaces  of  the  connective  tissue  abutting  here  and  there  against  the  lymphatics. 

the  tissues  outside  of  themselves  and  the  regular  lymphatic 
vessels  into  which  they  open.1 

In  structure,  the  larger  lymphatic  vessels  closely  resemble 
the  veins,  except  that  their  walls  are  somewhat  thinner  and 
more  transparent,  and  are  more  abundantly  supplied  with 
valves.  The  valves  are  constructed  and  arranged  in  the  same 
fashion  as  those  of  the  veins,  but  follow  one  another  at  such 
short  intervals,  that,  when  distended,  they  give  the  vessel  a 
beaded  or  jointed  appearance.  They  are  usually  wanting  in 
the  smaller  networks.  The  valves  allow  the  passage  of  mate- 
rial from  the  smaller  lymphatics  to  the  veins,  and  obstruct 
the  flow  of  anything  in  the  Apposite  direction.  The  lymphatics 
do  not  carry  to  the  tissues.  /Their  office  is  to  carry  away  from 
the  tissues  into  the  veins  all  the  material  the  tissues  do  not  need. 

1  The  serous  cavities  may  be  regarded  as  expanded  lymph  spaces,  as  they 
open  by  means  of  their  stpmata  into  the  lymphatics,  and  the  fluid  which 
moistens  their  surfaces  is  really  lymph  and  not  serum. 


CHAP.  XI.]  THE   VASCULAB   SYSTEM.  121 

The  lymphatics,  having  attained  a  certain  size,  do  not  unite 
into  larger  and  larger  trunks,  but  continue  of  the  same  diameter 
until  they  finally  enter  two  trunks  or  ducts  through  which 
their  contents  are  poured  into  the  veins.  The  lymphatics  from 
the  right  arm,  and  right  side  of  the  head,  neck,  and  upper  part 
of  the  trunk,  enter  the  right  lymphatic  duct.  The  vessels  from 
the  rest  of  the  body,  including  the  lacteals  from  the  intestines, 
enter  the  thoracic  duct.  As  we  have  stated  elsewhere  (page 
105),  these  ducts  pour  their  contents  into  the  blood  at  the 
junction  of  the  internal  jugular  and  subclavian  veins. 

The  lymph,  like  the  blood  in  the  veins,  is  returned  from  the 
limbs  and  viscera  by  a  deep  and  by  a  superficial  set  of  vessels. 
In  their  course  from  origin  to  termination  most  of  the  lym- 
phatics pass  through  small  masses  of  tissue,  called  lymphatic 
glands,  a  description  of  which  will  be  given  later  on. 

The  thoracic  duct.  —  The  thoracic  duct,  from  fifteen  to  eigh- 
teen inches  long  in  the  adult,  extends  from  the  second  lum- 
bar vertebra  to  the  root  of  the  neck.  It  lies  in  front  of  the 
bodies  of  the  vertebrae  gradually  inclining  towards  the  left 
until,  when  on  a  level  with  the  seventh  cervical  vertebra,  it 
turns  outward  and  arches  downwards  and  forwards  to  terminate 
in  the  angle  formed  by  the  junction  of  the  left  internal  jugular 
and  subclavian  veins.  The  size  is  usually  compared  to  that  of 
a  goose  quill.  It  is  dilated  below  where  it  receives  the  lym- 
phatics from  the  lower  limbs  and  the  chyle ,  from  the  lacteals, 
the  dilatation  being  known  as  the  receptaculum  chyli,  recep- 
tacle of  the  chyle.  The  duct  is  provided  with  valves,  and  in 
other  respects  closely  resembles  the  larger  lymphatics  in  struc- 
ture. It  is  often  alternately  contracted  and  enlarged  at  irregular 
intervals. 

The  right  lymphatic  duct  is  a  short  vessel  usually  from  a  quar- 
ter to  half  an  inch  in  length.  It  pours  its  contents  into  the 
blood  at  the  junction  of  the  right  internal  jugular  and  sub- 
clavian veins. 

The  lymph.  —  The  lymph  is  blood  minus  certain  constituents. 
When  examined  with  the  microscope,  it  is  seen  to  consist  of  a 
clear  liquid  with  corpuscles  floating  in  it.  The  liquid  part 
resembles  the  plasma  of  the  blood  in  its  composition,  except 
that  it  contains  relatively  more  water  and  less  solids.  It  clots 
when  removed  from  the  body,  though  not  so  firmly  as  the 


122  ANATOMY  FOR  NURSES.  [CHAP.  XI. 

blood.  The  lymph  corpuscles,  usually  called  leucocytes,  agree 
in  their  characters  with  the  white  corpuscles  of  the  blood. 
They  vary  in  number  in  different  parts,  being  more  numerous 
in  the  lymph  which  has  passed  through  the  lymphatic  glands 
than  in  that  which  enters  these  bodies,  thus  indicating  the  lym- 
phatic glands  as  a  source  of  these  corpuscles. 

The  chyle  in  the  lacteals  during  digestion  has  a  white  aspect 
dependent  upon  the  fatty  particles  absorbed  from  the  food,  and 
suspended  in  it  like  oil  globules  in  milk.  After  fasting  the 
lacteals  contain  lymph  which  differs  very  little  from  the  lymph 
found  in  the  ordinary  lymphatics. 

The  lymph,  broadly  speaking,  is  blood  minus  its  red  corpuscles. 
The  chyle  is  lymph  plus  a  very  large  quantity  of  minutely 
divided  fat. 

Movements  of  the  lymph.  —  The  onward  progress  of  the  lymph 
from  the  tissues  to  the  veins  is  maintained  chiefly  by  three 
things.  (1)  The  difference  of  the  pressure  upon  the  lymph  in 
the  tissues,  and  the  pressure  in  the  large  veins  of  the  neck.  As 
we  have  already  seen  in  our  last  chapter  the  pressure  exerted 
upon  the  blood  in  the  capillaries  is  greater  than  that  exerted 
upon  the  blood  in  the  veins.  This  pressure  in  the  smaller  blood- 
vessels is  communicated  through  the  blood-plasma  to  the  lymph, 
and  thus,  though  the  lymph  is  not  subjected  to  the  same  amount 
of  pressure  as  the  blood  in  the  capillaries,  it  still  stands  at  a 
higher  pressure  than  the  blood  in  the  veins.  We  may  consider 
the  lymphatics  to  form  a  system  of  vessels  leading  from  a  region 
of  higher  pressure,  viz.  the  lymph-spaces  of  the  tissues,  to  a 
region  of  lower  pressure,  viz.  the  interior  of  the  large  veins  of 
the  neck.  (2)  On  account  of  the  numerous  valves  in  the 
lymphatics  every  pressure  upon  the  tissues  in  which  they  lie 
will,  by  compressing  the  vessels,  cause  an  outward  flow  of  their 
contents.  Active  muscular  exercise  and  the  manipulation  of 
the  tissues,  as  practised  in  massage,  markedly  affect  the  lymph 
flow.  (3)  During  each  inspiration  the  pressure  on  the  thoracic 
duct  is  less  than  on  the  lymphatics  outside  the  thorax,  and  the 
lymph  is  accordingly  "sucked"  into  the  duct.  During  the 
succeeding  expiration  the  pressure  on  the  thoracic  duct  is  in- 
creased, and  some  of  its  contents,  prevented  by  the  valve  from 
escaping  below,  are  pressed  out  into  the  veins. 

The  lymph  in  the  various  lymph-spaces  of  the  body  varies  in 


CHAP.  XL]  THE   VASCULAR   SYSTEM.  123 

amount  from  time  to  time,  but  under  normal  circumstances, 
never  exceeds  certain  limits.  Under  abnormal  conditions,  these 
limits  may  be  exceeded,  and  the  result  is  known  as  oadema  or 
dropsy.  Similar  excessive  accumulations  may  also  occur  in  the 
larger  lymph-spaces,  the  serous  cavities. 

The  possible  causes  of  oedema  are,  on  the  one  hand,  an  ob- 
struction to  the  flow  of  lymph  from  the  lymph-spaces,  and  on 
the  other  hand,  an  excessive  trans udation,  the  lymph  gathering 
in  the  lymph-spaces  faster  than  it  can  be  carried  away  by  a 
normal  flow.  QEdema  is  almost  always  due  to  the  latter  cause, 
viz.  excessive  transudation. 

The  inflammatory  oedema,  due  to  changes  in  the  walls  of  the 
blood-vessels,  we  have  already  touched  on  in  speaking  of  the 
capillary  circulation.  In  this  kind  of  oedema  the  transudation 
is,  besides  being  crowded  with  migrating  corpuscles,  more  dis- 
tinctly coagulable  than  ordinary  lymph.  Allied  to  this  inflam- 
matory oedema  is  the  "effusion,"  which  appears  in  the  serous 
cavities  when  they  are  inflamed,  as  in  pleurisy  and  peritonitis. 

Functions  of  the  lymph.  — •  The  lymph  derived  from  the  blood 
delivers  to  the  elements  of  the  tissues  the  material  each  element 
needs  to  maintain  its  functional  activity,  and  returns  to  the 
blood  the  products  of  this  activity,  which  products  may  be 
simple  waste,  or  matters  capable  of  being  made  use  of  by  some 
other  tissue.  There  is  thus  a  continual  interchange  going  on 
between  the  blood  and  the  lymph.  How  this  interchange 
is  effected  may  be  partially  understood  by  the  following 
illustration. 

If  a  tumbler  be  completely  divided  vertically  into  two  com- 
partments by  a  moist  piece  of  memlprane,  and  a  watery  solution 
of  common  salt  be  placed  in  one  compartment,  and  a  watery 
solution  of  sugar  in  the  other,  it  will  be  found  after  a  time  that 
some  of  the  salt  has  found  its  way  into  the  solution  of  sugar, 
and,  vice  versa,  some  of  the  sugar  into  the  salt  solution.  Such 
an  interchange  is  said  to  be  due  to  dialysis  or  osmosis ;  and  if 
the  process  were  allowed  to  go  on  for  some  hours,  the  same 
proportion  of  salt  and  sugar  would  be  found  in  the  solutions  on 
each  side  of  the  dividing  membrane.  So  in  the  living  body. 
The  lymph,  originally  like  the  blood-plasma  (it  is  blood-plasma 
forced  to  transude  through  the  capillaries  by  the  pressure  of  the 
blood),  becomes  altered  by  the  metabolic  changes  of  the  tissues 


124 


ANATOMY   FOR  NURSES. 


[CHAP.  XL 


which  it  bathes,  and  we  have  two  different  fluids,  separated  by 
the  moist  membrane  which  forms  the  walls  of  the  blood-vessels, 
—  the  lymph  in  the  tissues  outside  the  walls  of  the  capillaries 
and  the  blood  inside  the  capillary  walls,  —  and  the  same  condi- 
tions may  be  said  to  exist  as  in  the  salt  and  sugar  solutions  just 
spoken  of.  And  now  the  same  phenomena  take  place ;  for 
though  the  pressure  is  higher  in  the  blood-vessels  than  in  the 

lymph  outside,  some  of  the  constitu- 
ents of  the  lymph  pass  into  the  blood 
by  the  process  of  osmosis. 

These  constituents,  which,  as  we 
cannot  too  often  emphasize,  are  prod- 
ucts resulting  from  the  activity  of 
the  tissues,  are  carried  away  by  the 
blood  to  other  tissues,  which  will 
either  make  use  of  them,  or,  as  in 
the  kidneys,  take  them  up  to  make 
excretory  fluids,  and  so  remove  them 
from  the  body. 

In  consequence  of  the  different 
wants  and  wastes  of  different  tissues 
at  different  times,  both  the  lymph 
and  blood  must  vary  in  composition 
in  different  parts  of  the  body.  But 
the  loss  and  gain  is  so  fairly  balanced 
that  the  average  composition  is  pretty 
constantly  maintained.  The  blood,  on 
account  of  the  higher  pressure,  loses 
more  liquid  to  the  lymph  than  it  re- 
ceives back,  but  this  excess  is  returned 
back  again  to  the  blood  by  the  lym- 
phatics when  they  empty  their  con- 
tents into  the  veins. 

Lymphatic  glands.  —  The  lymphatic 
glands  are  small,  solid  bodies,  placed 
in  the  course  of  the  lymphatics  and 
lacteals,  through  which  the  contents 
of  most  of  these  vessels  have  to  pass  in  their  progress  towards 
the  thoracic  and  right  lymphatic  ducts.  These  bodies  are  col- 
lected in  numbers  alongside  of  the  great  muscles  of  the  neck, 


FIG.  85.  —  LYMPHATICS  AND 
LYMPHATIC  GLANDS  OF  AXILLA 
AND  ARM. 


CHAP.  XI.] 


THE   VASCULAR   SYSTEM. 


125 


and  also  in  the  thorax  and  abdomen,  especially  in  the  mesentery, 
where  they  are  called  the  mesenteric  glands,  and  alongside 
of  the  aorta,  vena  cava  inferior,  and  the  iliac  vessels.  A  few, 
usually  of  small  size,  are  found  on  the  external  parts  of  the 
head,  and  considerable  groups  are  situated  in  the  axilla,  and 
in  the  groin,  where  they  receive  the  name  of  inguinal  glands. 
Some  three  or  four  lie  on  the  popliteal  vessels,  and  usually  one 
is  placed  a  little  below  the  knee,  but  none  farther  down.  In 
the  arm,  they  are  found  as  low  as  the  elbow  joint. 

The  size  of  the  lymphatic  glands  is  very  various,  some  being 
not  much  larger  than  a  hemp  seed,  and  others  as  large  as  an 
almond,  or  even  larger  than  this.  In  shape,  they  are  usually 
oval. 

A  lymphatic  gland  is  covered  by  an  envelope,  or  capsule,  of 
connective  and  muscular  tissue.  This  capsule  sends  fibrous 


FIG.  86.  —  DIAGRAMMATIC  SECTION  OF  LYMPHATIC  GLAND.  (Sharpey.)  a./, 
afferent  lymphatic;  e.l,  efferent  lymphatic;  c,  capsule,  or  envelope;  tr,  trabeculae; 
l.s,  lymph-sinus ;  l.h,  pulpy  substance  of  gland. 

bands  (trabeculce)  into  the  substance  of  the  gland,  dividing  the 
exterior  portion  into  more  or  less  regular  compartments,  and 
the  interior  into  irregular  labyrinths.  This  framework  is  occu- 


126 


ANATOMY   FOR   NURSES. 


[CHAP.  XT. 


pied  by  reticular  or  lymphoid  tissue,1  the  fine  meshes  of  which 
are  filled  with  leucocytes.  Between  this  pulpy  substance  of  the 
gland  and  the  skeleton  framework  there  is  a  narrow  space  (left 
white  in  the  diagram)  which  looks  as  if  the  pulp  had  originally 
filled  the  framework  and  then  shrunk  away  slightly  on  all  sides. 
The  spaces  thus  left  form  channels  for  the  passage  of  the  lymph, 
which,  entering  the  more  convex  surface  by  afferent  vessels, 
issues,  after  circulating  through  the  gland,  by  efferent  vessels 
below.  In  its  passage  through  the  gland  the  lymph  takes  up 
fresh  leucocytes,  which  are  continually  multiplying  by  cell 
division  in  the  glandular  substance.  The  lymphatic  glands  are 
plentifully  supplied  with  blood. 

Solitary  follicles  and  Peyer's  patches.  —  Closely  connected  with 
the  lymphatic  vessels  in  the  intestines  are  small,  rounded  bodies 


FIG.  87. — VERTICAL  SECTION  OF  A  PORTION  OF  A  PEYER'S  PATCH,  WITH  LAC- 
TEAL VESSELS  INJECTED,  a,  villi,  with  their  lacteals  coloured  black  ;  d,  surface  of 
rounded  follicle,  or  solitary  gland;  e,  central  part;  /,  g,  h,  i,  and  k,  lymph-channels, 
or  lacteal  vessels,  coloured  black. 

of  the  size  of  a  small  pin's  head,  called  solitary  glands  or  follicles. 
These  bodies  consist  of  a  rounded  mass  of  fine  lymphoid  tissue, 
the  meshes  of  which  are  crowded  with  leucocytes.  Into  this 
mass  of  tissue  one  or  more  small  arteries,  enter  and  form  a 

1  Reticular  or  lymphoid  tissue  is  that  variety  of  connective  tissue  in  which 
the  branched  connective  tissue  cells  unite  to  form  delicate  networks.  The 
meshes  of  the  network  are  occupied  by  fluid  in  which  the  leucocytes  often,  in 
large  numbers,  wander  to  and  fro. 


CHAP.  XI.]  THE   VASCULAR   SYSTEM.  127 

capillary  network,  from  which  the  blood  is  carried  away  by  one 
or  more  small  veins.  Surrounding  the  mass  are  lymph  channels 
which  are  continuous  with  the  lymphatic  vessels  in  the  tissue 
below. 

A  Peyer's  patch,  or  "  agminated  gland,"  as  it  is  often  called,  is 
simply  a  collection  of  these  follicles.  A  well-formed  Peyer's 
patch  consists  of  fifty  or  more  of  these  solitary  follicles,  ar- 
ranged in  a  single  layer,  close  under  the  epithelium  of  the 
intestinal  mucous  membrane,  and  stretching  well  down  into 
the  tissue  beneath.  These  patches  are  circular  or  oval  in  shape, 
and  from  twenty  to  thirty  in  number.  They  are  largest  and 
most  numerous  in  the  portion  of  the  intestine  called  the  ilium. 
They  increase  in  size  during  digestion. 

The  tonsils  are  two  thick  masses  of  lymphoid  tissue,  placed 
one  on  each  side  of  the  fauces  or  throat,  into  which  they  pro- 
ject. They  are  covered  by  stratified  epithelium,  and  their  sur- 
faces are  pitted  with  apertures  which  lead  into  recesses  or  crypts 
in  the  substance  of  the  tissue. 

The  spleen.  —  The  spleen  differs  in  many  important  particu- 
lars from  lymphatic  glands,  but  may  be  conveniently  studied  in 
conjunction  with  them,  as  it  resembles  these  glands  in  structure, 
and  is  functionally  connected  with  the  blood. 

Like  the  lymphatic  glands,  the  spleen  is  covered  by  a  fibrous 
and  muscular  capsule  which  sends  fibrous  bands  to  form  a  net- 
work in  the  interior  of  the  organ.  In  the  meshes  of  the  fibrous 
framework  lies  a  soft  pulpy  substance  containing  a  large 
amount  of  blood,  and,  therefore,  of  a  deep  red  colour.  This 
soft,  red  pulp  is  dotted  with  whitish  specks,  which  are  small 
masses  of  lymphoid  tissue,  and  are  called  the  Malpighian  cor- 
puscles of  the  spleen. 

The  blood  supplied  to  the  spleen  appears  to  escape  from  the 
minute  subdivisions  of  the  arteries  into  the  red  pulp  before 
entering  the  exceedingly  thin-walled  veins  by  which  it  is  con- 
veyed from  the  gland.  The  pulp  contains  numerous  red  cor- 
puscles, and  many  bodies  which  appear  to  be  red  corpuscles  in 
process  of  decay  or  destruction,  and  it  is  surmised  that  the  red 
corpuscles  are  in  some  way  destroyed,  and  that  additional  white 
corpuscles  are  formed,  within  the  spleen. 

The  spleen  is  covered  by  a  portion  of  the  peritoneum,  the 
serous  membrane  covering  the  viscera  of  the  abdomen,  and 


128  ANATOMY  FOB  NURSES.  [CHAP.  XI. 

lies  upon  the  left  side  of  the  stomach,  in  the  abdominal  cavity. 
It  is  an  elongated,  flat  body,  varying  greatly  in  size  at  different 
periods  of  life.  The  size  is  increased  during  and  after  diges- 
tion, and  is  always  large  in  well-fed,  and  small  in  starved, 
animals.  In  certain  diseases,  and  more  especially  in  ague,  a 
temporary  enlargement  takes  place.  In  prolonged  ague,  a  per- 
manent enlargement  of  the  spleen  occurs,  and  forms  the  so- 
called  "ague  cake." 


CHAPTER  XII. 

THE  RESPIRATORY  APPARATUS:  LARYNX;  TRACHEA;  LUNGS. 
RESPIRATION;  EFFECTS  OF  RESPIRATION  UPON  THE  AIR 
WITHIN  THE  LUNGS,  UPON  THE  AIR  OUTSIDE  THE  BODY, 
UPON  THE  BLOOD;  MODIFIED  RESPIRATORY  MOVEMENTS. 

The  respiratory  apparatus.  —  Respiration  is  the  main  process 
by  means  of  which  the  body  is  supplied  with  oxygen  and  re- 
lieved of  carbonic  acid. 

A  respiratory  apparatus  consists  essentially  of  a  moist  and 
permeable  membrane,  with  blood-vessels  containing  carbonic 
acid  on  one  side,  and  air  or  fluid  containing  oxygen  on  the 
other.  In  most  aquatic  animals,  the  respiratory  organs  have 
the  form  of  gills;  in  terrestrial  or  air-breathing  animals,  the 
respiratory  organs  are  situated  internally  under  the  form  of 
lungs,  and  are  placed  in  communication  with  the  external  air 
by  a  tube  or  windpipe. 

In  man,  the  respiratory  apparatus  may  be  conveniently  di- 
vided into  the  larynx,  trachea,  and  lungs. 

The  larynx.  —  The  larynx  is  situated  between  the  base  of  the 
tongue  and  the  top  of  the  trachea,  in  the  upper  and  front  part 
of  the  neck.  Above  and  behind  lies  the  pharynx,  which  opens 
into  the  oesophagus  or  gullet,  and  on  either  side  of  it  lie  the  great 
vessels  of  the  neck. 

The  larynx  is  made  up  of  nine  pieces  of  cartilage,  united 
together  by  ligaments,  and  moved  by  numerous  muscles.  It  is 
lined  throughout  by  mucous  membrane,1  which  is  continuous 
above  with  that  lining  the  pharynx,  and  below  with  that  lining 
the  trachea.  In  form,  the  larynx  is  narrow  and  rounded  below 

1  Mucous  membranes  resemble  the  skin  in  structure,  and  may  be  said  to 
form  an  internal  skin  for  the  cavities  of  the  body  which  open  exteriorly.    They 
always  have  a  basis  of  connective  tissue,  are  lined  with  epithelium,  and  secrete 
a  sticky  substance  called  mucus.    For  a  further  description,  see  page  144. 
it  129 


130 


ANATOMY   FOR  NUKSES.  [CHAP.  XII. 


where  it  blends  with  the  trachea,  but  broad  above,  and  shaped 
somewhat  like  a  triangular  box,  with  flat  sides  and  prominent 
ridge  in  front.  This  prominence,  popularly  called  "Adam's 
apple,"  is  formed  by  the  union  of  the  two  largest  pieces  of 
cartilage  (the  thyroid),  of  which  the  larynx  is  composed. 

Across  the   middle   of  the  larynx  is  a  transverse   partition, 

formed  by  two  folds  of  the  lining- 
mucous  membrane,  stretching  from 
side  to  side,  but  not  quite  meeting 
in  the  middle  line.  They  thus 
leave  in  the  middle  line  a  chink  or 
slit,  running  from  front  to  back, 
called  the  glottis  or  rima  glottidis. 
Imbedded  in  the  mucous  mem- 
branes at  the  edges  of  the  slit  are 
fibrous  and  elastic  ligaments,  which 
strengthen  the  edges  of  the  glottis 
and  give  them  elasticity.  These 
ligamentous  bands,  covered  with 
the  mucous  membrane,  are  firmly 
attached  at  either  end  to  the  car- 
tilages of  the  larynx,  and  are 
called  the  vocal  cords.  The  space 
left  between  their  edges,  the  glottis* 
varies  in  shape  and  size,  according 
to  the  action  of  the  muscles  upon 

PHARYNX,  WITH  THE  "COMMEND  the  laryngeal  walls.  When  the 
MENT  OF  GULLET  AND  LARYNX,  AS  larynx  is  at  rest  during  quiet 

EXPOSED  BY  A  SECTION  A  LITTLE  TO    ,  J  ,    .  ,      .  .  . 

THE  LEFT  OF  THE  MED^N  PLANE  OF  breathing,  the  glottis  is  V-shaped; 
THE  HEAD,  a,  vertebrae ;  6,  gullet ;  during  a  deep  inspiration,  it  be- 

c,  trachea;  d,  larynx;    e,  epiglottis;  ,         ,  .,        , 

/,  soft  palate;  g,  opening  of  Eus-  comes  almost  round;  while,  during 
tachian  tube;  k,  tongue;  i,  hard  the  production  of  a  high  note,  the 

palate;    o,  p,   q,  inferior    turbinate 

bones  of  left  nasal  chamber.  edges  of  the  cords  approximate  so 

closely   as   to  leave  scarcely    any 

opening  at  all.  The  glottis  is  protected  by  a  leaf-shaped  lid  of 
fibro-cartilage,  called  the  epiglottis,  which  shuts  down  upon  the 
opening  during  the  passage  of  food  or  other  matters  into  the 
oesophagus. 

The  vocal  cords  produce  the  voice.     A  blast  of  air,  driven  by 
an    expiratory  movement   out   of   the   lungs,  throws   the  two 


FIG.  88.  —  THE  MOUTH,  NOSE,  AND 


CHAP.  XII.] 


KESPIKATIOK 


131 


elastic  cords  into  vibrations.  These  impart  their  vibrations  to 
the  column  of  air  above  them,  and  so  give  rise  to  the  sound 
which  we  call  the  voice. 

The  larynx  is  placed  in  communication  with  the  external  air 
by  two  channels:  the  one,  supplied  by  the  nasal  passages,  is 
always  open ;  the  other,  furnished  by  the  mouth,  can  be  opened 
and  closed  at  will. 
One  advantage  of  this 
arrangement  is,  'that 
when  exposed  to  a 
very  cold  temperature, 
we  can  close  our 
mouths  and  breathe 
through  the  nasal  pas- 
sages, which,  being  nar- 
row, thickly  lined,  and 
freely  supplied  with 
blood  -  vessels,  warm 
the  air  before  it  reaches 
the  lungs. 

The  trachea.  —  The 
trachea  or  windpipe  is 
a  fibrous  and  muscu- 
lar tube,  the  walls  of 
which  are  strengthened 
and  rendered  more 
rigid  by  hoops  of  car-  FIG.  89.  — THE  LARYNX  AS  SEEN  BY  MEANS  OF 
tilage  embedded  in  the  THE  LARYNGOSCOPE  IN  DIFFERENT  CONDITIONS 

{  OF  THE  GLOTTIS.    A,  while  singing  a  high  note ;  B, 

fibrous  tissue.      These 


hoom 


in  quiet  breathing;    (7,  during  a  deep  inspiration. 

'»  base  of  tonSue;  e>  uPPer  free  edSe  of  epiglottis  ; 

e',  cushion  of  the  epiglottis  ;  ph,  part  of  anterior 
and  incomplete  behind,  wall  of  pharynx;  cv,  the  true  vocal  cords;  cvs,  the 
tllP  Pflr  til  a  crin  mi-  rinrr*  false  VOCal  CO1'ds  '  tr>  the  trachea  with  its  ***&'>  6' 

tne  cartilaginous  rings  the  two  bronchi  at  their  corainencement. 
being     completed     by 

bands  of  plain  muscular  tissue  where  the  trachea  comes  in  con- 
tact with  the  oasophagus.  Like  the  larynx  it  is  lined  by  mucous 
membrane,  and  has  a  ciliated  epithelium  upon  its  inner  surface. 
The  mucous  membrane,  which  also  extends  into  the  bronchial 
tubes,  keeps  the  internal  surface  of  the  air  passages  free  from 
impurities;  the  sticky  mucus  entangles  particles  of  dust  and 
other  matters  breathed  in  with  the  air,  and  the  incessant 


132  ANATOMY   FOE,  NUESES.  [CHAP.  XII. 

movements   of   the   cilia   continually  sweep   this   dirt-ladened 
mucus  upwards  and  outwards. 

The  trachea  measures  about  four  and  a  half  inches  in  length, 


FIG.  90.  —  FRONT  VIEW  OF  CARTILAGES  OF  LARYNX.    Trachea  and  bronchi. 

and  three-quarters  of  an  inch  from  side  to  side.  It  extends 
down  into  the  thorax  from  the  lower  part  of  the  larynx  to 
opposite  the  third  dorsal  vertebra,  where  it  divides  into  two 
tubes,  —  the  two  bronchi,  —  one  for  each  lung. 


CHAP.  XII.] 


RESPIKATION. 


133 


The  lungs.  —  The  lungs  consist  of  the  bronchial  tubes  and 
their  terminal  dilatations,  numerous  blood-vessels,  lymphatics, 
and  nerves,  and  an  abundance  of  fine,  elastic,  connective  tissue, 
binding  all  together. 

The  two  bronchi,  into  which  the  trachea  divides,  enter  the 
right  and  left  lung  respectively,  and  then  break  up  into  a  great 
number  of  smaller  branches  which  are  called  the  bronchial 
tubes.  The  two  bronchi  resemble  the  trachea  in  structure ;  but 
as  the  bronchial  tubes  divide  and  subdivide,  their  walls  become 
thinner,  the  small  plates  of  cartilage  drop  off,  the  fibrous  tissue 
disappears,  and  the  finer  tubes  are  composed  of  only  a  thin 
layer  of  muscular  and  elastic  tissue,  lined  by  mucous  membrane. 
Finally,  these  finer  tubes  end  in 
dilated  cavities,  the  walls  of  which, 
consisting  of  a  single  layer  of  flat- 
tened epitheloid  cells,  surrounded 
by  a  fine,  elastic,  connective  tissue, 
are  exceedingly  thin  and  delicate. 

Immediately  beneath  the  layer  of 
flat  cells,  and  lodged  in  the  elastic 
connective  tissue,  is  a  very  close 
network  of  capillary  blood-vessels; 
and  the  air  reaching  the  terminal 
dilatations  by  the  bronchial  tubes  is 
separated  from  the  blood  in  the 
capillaries  by  only  the  thin  mem- 
branes forming  their  respective 
walls. 

The  terminal  dilatations  do  not  end  as  simple,  rounded  sacs, 
like  children's  air-balloons,  but  each  bronchiole  ends  in  an 
enlargement  having  more  or  less  the  shape  of  a  funnel,  and 
called  an  infundibulum.  Each  of  these  infundibula  is  sub- 
divided into  secondary  chambers  or  cavities,  called  alveoli,  the 
walls  of  which  are  honey-combed  with  "  bulgings." *  In  this 
way  the  amount  of  surface  exposed  to  the  air  and  covered  by 
the  capillaries  is  immensely  increased.2 

1  These  protrusions  may  be  illustrated  by  a  pea-pod,  the  walls  of  which  are 
filled  with  "  bulgings,"  made  by  the  pressure  of  the  peas. 

2  The  pulmonary  alveoli  are  often  spoken  of  under  the  general  name  of  air- 
sacs,  and  the  "bulgings  "  are  known  as  air-cells. 


FIG.  91. —  Two  ALVEOLI  OF  THE 
LUNG.  Highly  magnified.  6,  &, 
the  air-cells,  or  bulgings,  of  the 
alveoli,  a,  a. 


134  ANATOMY   FOR,   NURSES  [CHAP.  XII. 

Broadly  speaking,  the  lungs  may  be  said  to  consist  of  a  large 
amount  of  a  film-like  elastic  membrane,  covered  by  a  close  net- 
work of  blood-vessels,  which  membrane  is  arranged  in  the  form 
of  irregularly  dilated  pouches  at  the  end  of  fine  tubes,  opening 
into  larger  and  larger  tubes,  and  finally  into  the  windpipe, 
which  places  them  in  communication  with  the  external  air. 

By  virtue  of  their  structure,  the  larger  bronchial  tubes 
remain  permanently  open ;  the  smaller  tubes,  however,  are  sub- 


FIG.  92.  —  ANTERIOR  VIEW  OF  LUNGS  AND  HEART.  1,  heart;  2,  inferior  vena 
cava ;  3,  superior  vena  cava ;  4,  right  innominate  vein ;  5,  left  innominate  vein  ; 
6,  jugular  vein;  7,  subclavian  vein;  8,  arch  of  aorta;  8',  subclavian  artery;  9,  left 
pulmonary  artery;  9',  9',  carotid  artery;  10,  trachea;  11,  left  bronchus;  12,  rami- 
fications of  right  bronchus  exposed  in  upper  lobe  of  right  lung ;  13,  14,  middle  lobe ; 
15,  lower  lobe;  It),  upper  lobe  of  left  lung;  17,  lower  lobe  of  left  lung. 

ject  to  collapse  when  empty;  they  also  may  contract  under 
certain  nervous  influences.  The  terminal  dilatations  are  emi- 
nently elastic  and  continually  expand  and  contract;  they  are 
bathed  with  lymph,  and  are  always  moist. 

The  two  lungs  occupy  almost  all  the  cavity  of  the  thorax 
which  is  not  taken  up  by  the  heart.  The  right  lung  is  the 
larger  and  heavier;  it  is  broader  than  the  left,  owing  to  the 
inclination  of  the  heart  to  the  left  side  ;  it  is  also  shorter  by  one 


CHAP.  XII.]  RESPIRATION.  135 

inch,  in  consequence  of  the  diaphragm  rising  higher  on  the  right 
side  to  accommodate  the  liver.  The  right  lung  is  divided  by 
fissures  into  three  lobes.  The  left  lung  is  smaller,  narrower, 
and  longer  than  the  right,  and  has  only  two  lobes.  Each  lung 
is  enclosed  in  a  serous  sac,  the  pleura,  one  layer  of  which  is 
closely  adherent  to  the  walls  of  the  chest  and  diaphragm ;  the 
other  closely  covers  the  lung.  The  base  of  each  lung  is  at- 
tached, by  means  of  the  pleura,  to  the  diaphragm,  and  the  apex 
is  attached  above  the  margin  of  the  first  rib.  The  two  layers 
of  the  pleural  sacs,  moistened  by  lymph,  are  normally  in  close 
contact ;  they  move  easily  upon  one  another,  and  prevent  the 
friction  that  would  otherwise  occur  between  the  lungs  and  the 
walls  of  the  chest  with  every  respiration. 

The  pressure  of  the  atmospheric  air  upon  the  lungs  through 
the  air-passages  is  greater  than  it  can  possibly  be  upon  them 
from  the  outside  through  the  chest  walls,  on  account  of  the 
resistance  which  the  solid  chest  walls  offer  to  this  pressure ; 
and,  ordinarily,  it  is  impossible  for  the  lungs  to  pull  away 
the  layer  of  the  pleural  sac  which  adheres  to  them  from  the 
layer  which  is  attached  to  the  chest  wall.  If,  however,  the 
chest  wall  be  punctured,  the  air  from  the  outside  will  rush  in, 
distend  the  pleura,  and,  squeezing  the  air  out  of  the  air-sacs  into 
the  air-passages,  cause  the  lungs  to  shrivel  up  and  collapse. 

Respiration.  —  The  lungs,  then,  are  placed  in  an  air-tight  tho- 
rax, which  they,  together  with  the  heart  and  great  blood-vessels, 
completely  fill.  By  the  contraction  of  certain  muscles  (see  page 
65),  the  cavity  of  the  thorax  is  enlarged;  the  lungs  are  cor- 
respondingly distended  to  fill  the  enlarged  cavity,  and,  by  this 
distension,  the  air  within  the  air-sacs  becomes  expanded  and 
more  rarefied  than  the  air  outside.  Being  thus  expanded  and 
rarefied,  the  pressure  of  the  air  within  the  lungs  becomes  less 
than  that  of  the  air  outside,  and  this  difference  of  pressure 
causes  the  air  to  rush  through  the  trachea  into  the  lungs,  until 
an  equilibrium  of  pressure  is  established  between  the  air  inside 
the  lungs  and  that  outside.  This  constitutes  an  inspiration. 
Upon  the  relaxation  of  the  inspiratory  muscles,  the  elasticity 
of  the  lungs  and  the  chest  walls  causes  the  chest  to  return  to 
its  original  size,  in  consequence  of  which  the  air  within  the 
lungs  becomes  more  contracted  and  denser  than  the  air  outside, 
the  pressure  within  becomes  greater  than  the  pressure  without, 


136  ANATOMY  FOR  NURSES.  [CHAP.  XII. 

and  the  air  rushes  out  of  the  trachea  until  equilibrium  be  once 
more  established.  This  constitutes  an  expiration.  An  inspira- 
tion and  an  expiration  make  a  respiration. 

As  in  the  heart,  the  auricular  systole,  the  ventricular  systole, 
and  then  a  pause,  follow  in  regular  order,  —  so  in  the  lungs, 
the  inspiration,  the  expiration,  and  then  a  pause  succeed  one 
another.  Each  respiratory  act  in  the  adult  is  ordinarily  repeated 
from  fifteen  to  eighteen  times  per  minute.  But  this  rate  varies 
under  different  circumstances,  one  of  the  most  important  of 
which  is  age.  The  average  rate  in  the  newly  born  infant  has 
been  found  to  be  forty-four  per  minute,  and  at  the  age  of  five 
years,  twenty-six  per  minute.  It  is  reduced  between  the  ages 
of  fifteen  and  twenty  to  the  normal  standard. 

A  condition  of  rest  or  activity  readily  influences  the  number 
of  respirations  per  minute.  They  are  always  less  frequent 
during  sleep,  and  are  markedly  increased  by  severe  muscular 
exercise. 

Respiration  is  an  involuntary  act.  It  is  possible  for  a  short 
time  to  increase  or  retard  the  rate  of  respiration  within  certain 
limits  by  voluntary  effort,  but  this  cannot  be  done  continuously. 
If  we  intentionally  arrest  the  breathing  or  diminish  its  fre- 
quency after  a  short  time  the  nervous  impulse  becomes  too 
strong  to  be  controlled,  and  the  movements  will  recommence 
as  usual.  If,  on  the  other  hand,  we  purposely  accelerate  res- 
piration to  any  great  degree,  the  exertion  soon  becomes  too 
fatiguing  for  continuance,  and  the  movements  return  to  their 
normal  standard. 

The  nervous  impulses  which  cause  the  contractions  of  the 
respiratory  muscles  arise  in  the  medulla  oblongata,  travel  down 
the  spinal  cord,  and  out  along  the  phrenic  and  intercostal 
nerves.  If  the  portion  of  the  medulla  oblongata,  where  these 
nervous  impulses  arise,  be  removed  or  injured,  respiration 
ceases,  and  death  at  once  ensues.  This  part  of  the  medulla  is 
known  as  the  respiratory  centre,  and  is  also  often  called  the 
"vital  knot." 

The  effects  of  respiration  upon  the  air  within  the  lungs.  —  At 
birth  the  lungs  contain  no  air.  The  walls  of  the  air-sacs  are  in 
close  contact,  and  the  walls  of  the  smaller  bronchial  tubes  or 
bronchioles  collapsed  and  touching  one  another.  The  trachea 
and  larger  bronchial  tubes  are  open,  but  contain  fluid  and  not 


CHAP.  XIL]  RESPIRATION.  137 

air.  When  the  chest  expands  with  the  first  breath  taken,  the 
inspired  air  has  to  overcome  the  adhesions  existing  between 
the  walls  of  the  bronchioles  and  air-sacs.  The  force  of  this 
first  inspiratory  effort,  spent  in  opening  out  and  unfolding,  as  it 
were,  the  inner  recesses  of  the  lungs,  is  considerable.  In  the 
succeeding  expiration,  most  of  the  air  introduced  by  the  first 
inspiration  remains  in  the  lungs,  succeeding  breaths  unfold  the 
lungs  more  and  more,  until  finally  the  air-sacs  and  bronchioles 
are  all  opened  up  and  filled  with  air.  The  lungs  thus  once  filled 
with  air  are  never  completely  emptied  again  until  after  death. 

The  air  remaining  in  the  lungs  after  expiration  is  called  the 
old  or  stationary  air,  into  which  fresh  air  is  introduced  with 
every  inspiration,  the  fresh  or  tidal  air,  as  it  is  called,  giving 
up  its  oxygen  to,  and  taking  carbonic  acid  from,  the  old  or 
stationary  air.  Thus  the  stationary  air  transacts  the  business 
of  respiration,  receiving,  on  the  one  hand,  constant  supplies  of 
oxygen  from  the  tidal  air  which  it  delivers  to  the  blood  in  the 
capillaries  on  the  walls  of  the  air-sacs ;  and,  on  the  other  hand, 
returning,  in  exchange  to  the  tidal  air,  the  carbonic  acid  it  has 
received  from  the  blood  in  these  capillaries. 

In  ordinary  respiration  the  lungs  are  not  distended  to  their 
fullest  extent,  but  by  more  forcible  muscular  contraction  the 
capacity  of  the  chest  can  be  further  enlarged,  and  a  certain 
additional  amount  of  air  will  rush  into  the  lungs.  This  addi- 
tional amount  is  often  spoken  of  as  complemental  air.  In 
laboured  breathing  the  contraction  of  the  respiratory  muscles 
not  usually  brought  into  play,  such  as  the  muscles  of  the  throat 
and  nostrils,  becomes  very  marked. 

The  entry  and  exit  of  the  air  are  accompanied  by  respiratory 
sounds  or  murmurs.  These  murmurs  differ  as  the  air  passes 
through  the  trachea,  the  larger  bronchial  tubes,  and  the  bron- 
chioles. They  are  variously  modified  in  lung  disease,  and  are 
then  often  spoken  of  under  the  name  of  "  rales." 

The  effects  of  respiration  upon  the  air  outside  the  body.  —  With 
every  inspiration  a  well-grown  man  takes  into  his  lungs  about 
thirty  cubic  inches  of  air.  The  air  he  takes  in  differs  from  the 
air  he  gives  out  mainly  in  three  particulars :  — 

1.  Whatever  the  temperature  of  the  external  air,  the  expired 
air  is  nearly  as  hot  as  the  blood;  namely,  of  a  temperature 
between  98°' and  100°  F. 


138  ANATOMY   FOR,  NURSES.  [CHAP.  XII. 

2.  However  dry  the  external  air  may  be,  the  expired  air  is 
quite,  or  nearly,  saturated  with  moisture. 

3.  The  expired  air  contains  about  four  or  five  per  cent  less 
oxygen,  and  about  four  per  cent  more  carbonic  acid  than  the 
external  air,  the  quantity  of  nitrogen  suffering  but  little  change. 
Thus:  — 

Oxygen.  Nitrogen.  Carbonic  Acid. 

Inspired  air  contains    .     .    .    20.81  79.15  0.04 

Expired  air  contains    .     .     .     16.033  79.587  4.38 

(Foster.) 

In  addition  the  expired  air  contains  a  certain  amount  of  effete 
matter,  of  a  highly  decomposable  and  impure  character.  The 
quantity  of  water  given  off  in  twenty-four  hours  varies  very 
much,  but  may  be  taken  on  the  average  to  be  about  nine  ounces. 
The  quantity  of  carbon  given  off  at  the  same  time  is  pretty 
nearly  estimated  by  a  piece  of  pure  charcoal  weighing  eight 
ounces. 

If  a  man  breathing  fifteen  to  sixteen  times  a  minute  takes  in 
thirty  cubic  inches  of  air  with  each  breath,  and  exhales  the 
same  quantity,  it  follows  that  in  twenty-four  hours  from  three 
hundred  and  fifty  to  four  hundred  cubic  feet  of  air  will  have 
passed  through  his  lungs.  And  if  such  a  man  be  shut  up  in  a 
close  room  measuring  seven  feet  each  way,  all  the  air  in  the 
room  will  have  passed  through  his  lungs  in  twenty-four  hours. 

Since  at  every  breath  the  external  air  loses  oxygen  and  gains 
carbonic  acid  and  other  waste  and  poisonous  matters,  it  is 
imperative  that  some  provision  be  made  for  constantly  renewing 
the  atmospheric  surroundings  of  people  in  dwelling  houses. 
This  is  accomplished  by  ventilation,  which  consists  of  a  system 
of  mechanical  contrivances,  by  means  of  which  foul  air  is  con- 
stantly removed  and  fresh  air  as  constantly  supplied. 

The  minimum  amount  of  air  space  every  individual  should 
have  to  himself  is  800  cubic  feet  (a  room  nine  feet  high,  wide, 
and  long  contains  729  cubic  feet)  and  this  space  should  be 
accessible  by  direct  or  indirect  channels  to  the  outside  air. 

Effects  of  respiration  upon  the  blood.  —  While  the  air  in  passing 
into  and  out  of  the  lungs  is  robbed  of  a  portion  of  its  oxygen 
and  loaded  with  a  certain  quantity  of  carbonic  acid,  the  blood 
as  it  streams  along  the  pulmonary  capillaries  is  also  undergoing 
important  changes.  As  it  leaves  the  right  ventricle  it  is  venous 


CHAP.  XII.]  RESPIRATION. 

blood  of  a  dark  purple  colour ;  when  it  enters  the  left  auricle  it 
is  arterial  blood  and  of  a  bright  scarlet  colour.  In  passing 
through  the  capillaries  of  the  body  from  the  left  to  the  right 
side  of  the  heart  it  is  again  changed  from  the  arterial  to  the 
venous  condition.  The  question  arises,  how  is  this  change  of 
colour  effected? 

As  we  have  already  seen,  the  blood  in  the  thin- walled,  close- 
set  pulmonary  capillaries  is  separated  from  the  air  in  the  air- 
sacs  by  only  the'  moist  delicate  membranes  which  form  their 
respective  walls.  By  diffusion  the  oxygen  in  the  air  passes 
through  these  moist  membranes  into  the  venous  blood  in  the 
pulmonary  capillaries,  combines  with  the  reduced  haemoglobin 
which  has  lost  its  oxygen  in  the  tissues,  and  turns  it  into  oxy- 
haemoglobin  ;  the  purple  colour  shifts  immediately  into  scarlet, 
and  the  red  corpuscles  hasten  onwards  to  carry  this  oxy-haemo- 
globin to  the  tissues.  Passing  from  the  left  ventricle  to  the 
capillaries  in  the  tissues  the  oxy-haemoglobin  gives  up  some  of 
its  oxygen,  the  colour  shifts  back  again  to  a  purple  hue,  and 
the  red  corpuscles  return  with  this  reduced  haemoglobin  to  the 
lungs. 

The  oxygen  given  up  by  the  blood  combines  with  the  ele- 
ments of  the  tissues  and  forms  with  them  unstable  chemical 
compounds  which  are  always  breaking  down  to  form  more  sta- 
ble compounds,  called  "  oxides."  In  this  process,  which  is  called 
oxidation,  both  heat  and  force  are  produced  and  such  oxidized 
products  as  carbonic  acid  and  urea  are  evolved.1  The  carbonic 
acid  passes  by  diffusion  into  the  venous  blood,  and  is  carried  by 
it  to  the  right  side  of  the  heart  and  thence  to  the  lungs,  a 
certain  quantity,  however,  escaping  from  the  blood  through  the 
kidneys  and  skin.  A  small  and  insignificant  amount  of  oxygen 
is  introduced  into  the  blood  through  the  skin,  and,  with  the 
food,  through  the  alimentary  canal ;  but,  as  we  have  stated  in 
the  beginning  of  this  chapter,  respiration  is  the  main  process  by 
means  of  which  the  body  is  supplied  with  oxygen  and  relieved 
of  carbonic  acid. 

The  respiration  and  circulation  are  profoundly  and  intimately 

1  This  process  of  oxidation  may  be  illustrated  by  the  burning  of  a  fire  ;  the 
oxygen  which  is  in  the  air  combines  with  the  carbon  of  the  wood,  heat  and  light 
are  generated,  and  oxidized  products  in  the  form  of  carbonic  acid  and  ashes  pro- 
duced. 


140  ANATOMY  FOE   NURSES.  [CHAP.  XII. 

connected  together,  any  change  in  the  blood  immediately  affect- 
ing the  respiration. 

It  would  appear  that  stimulation  of  the  respiratory  centre  in 
the  medulla  oblongata  depends  primarily  upon  the  condition  of 
the  blood.  If  the  blood  is  very  rich  in  oxygen  the  respirations 
are  feeble  and  shallow ;  if,  on  the  other  hand,  the  blood  is  highly 
venous  the  respirations  are  deeper  and  more  frequent,  and  if  the 
blood  remains  venous,  gradually  become  forced  and  laboured 
until  we  get  the  condition  called  "  dyspnoea."  Should  the  blood 
get  more  and  more  venous,  the  impulses  generated  in  the  respir- 
atory centre  become  more  and  more  vehement.  These  nervous 
impulses,  instead  of  confining  themselves  to  the  usual  nerves 
distributed  to  the  ordinary  respiratory  muscles,  overflow  on  to 
other  nerves  and  put  into  action  other  muscles  until  there  is 
scarcely  a  muscle  in  the  body  that  is  not  affected.  The  muscles 
which  are  thus  more  and  more  thrown  into  action  are  especially 
those  tending  to  carry  out  or  to  assist  expiration ;  and  at  last  if 
no  relief  is  afforded  the  violent  respiratory  movements  give  way 
to  general  convulsions  of  the  whole  body.  By  the  violence  of 
these  convulsions  the  whole  nervous  system  becomes  ex- 
hausted, the  convulsions  soon  cease,  and  death  is  ushered  in 
with  a  few  infrequent  and  long-drawn  breaths. 

It  has  been  surmised  that  the  excitability  of  the  respiratory 
nerve-centre  is  due  to  certain  chemical  substances  which  act  as 
stimulants.  When  the  blood  is  rich  in  oxygen  this  substance  is 
oxidized  or  burned,  and  removed  so  fast  that  it  is  able  to  exert 
but  little  influence  on  the  respiratory  nerve-centre ;  when,  how- 
ever, the  blood  is  poor  in  oxygen,  this  substance  accumulates 
and  the  nerve-centre  is  powerfully  stimulated.  Thus  when  the 
'blood  needs  oxygen,  the  respirations  are  increased  to  get,  if 
possible,  more  air  into  the  lungs ;  if  the  blood  is  too  rich  in 
oxygen,  the  respirations  become  abnormally  quiet  and  shallow. 

Modified  respiratory  movements.  —  Various  emotions  may  be 
expressed  by  means  of  the  respiratory  apparatus. 

Sighing  is  a  deep  and  long-drawn  inspiration,  chiefly  through 
the  nose. 

Yawning  is  an  inspiration,  deeper  and  longer  continued  than 
a  sigh,  drawn  through  the  widely  open  mouth,  and  accompanied 
by  a  peculiar  depression  of  the  lower  jaw. 

Hiccough  is  caused  by  a  sudden,  inspiratory  contraction  of  the 


CHAP.  XIL]  RESPIRATION.  141 

diaphragm ;  the  glottis  suddenly  closes  and  cuts  off  the  column 
of  air  just  entering ,  which,  striking  upon  the  closed  glottis, 
gives  rise  to  the  characteristic  sound. 

In  sobbing,  a  series  of  convulsive  inspirations  follow  each 
other  slowly,  the  glottis  is  closed,  so  that  little  or  no  air  enters 
the  chest. 

Coughing  consists,  in  the  first  place,  of  a  deep  and  long-drawn 
inspiration  by  which  the  lungs  are  well  filled  with  air.  This  is 
followed  by  a  complete  closure  of  the  glottis,  and  then  comes  a 
forcible  and  sudden  expiration,  in  the  midst  of  which  the  glottis 
suddenly  opens,  and  thus  a  blast  of  air  is  driven  through  the 
upper  respiratory  passages. 

In  sneezing,  the  general  movement  is  the  same,  except  that 
the  opening  from  the  pharynx  into  the  mouth  is  closed  by  the 
contraction  of  the  pillars  of  the  throat  and  the  descent  of  the  soft 
palate,  so  that  the  force  of  the  blast  is  driven  entirely  through 
the  nose. 

Laughing  consists  essentially  in  an  inspiration,  followed  by  a 
whole  series  of  short  spasmodic  expirations,  the  glottis  being 
freely  open  during  the  whole  time,  and  the  vocal  cords  being 
thrown  into  characteristic  vibrations. 

In  crying,  the  respiratory  movements  are  the  same  as  in 
laughing ;  the  rhythm  and  the  accompanying  facial  expressions 
are,  however,  different,  though  laughing  and  crying  often  be- 
come indistinguishable. 


CHAPTER  XIII. 

ALIMENTATION. 

SECTION  I.  Preliminary  remarks  on  secreting  glands  and  mucous 
membranes. 

SECTION  II.  Food-principles ;  proteids,  fats,  carbo-hydrates,  water,  saline 
and  mineral  substances  :  chemical  composition  of  the  body :  average  compo- 
sition of  rnilk,  bread,  and  meat.  Concluding  remarks. 

SECTION  I.  In  our  last  chapter,  we  described  the  methods  by 
means  of  which  the  blood  was  supplied  with  its  most  vital  con- 
stituent, oxygen.  In  the  next  three  chapters,  we  shall  consider 
how  the  blood  is  supplied  with  those  materials  through  the  ali- 
mentary canal,  which  it  also  constantly  requires  to  maintain  the 
life  and  growth  of  the  body. 

The  subject  of  alimentation,  or  the  process  by  which  the 
body  is  nourished,  naturally  falls  into  three  divisions,  viz. :  — 

(1)  Food. 

(2)  Digestion. 

(3)  Absorption. 

In  order,  however,  to  make  the  subject  more  intelligible,  it 
will  be  necessary  to  make  a  few  preliminary  remarks  upon  the 
construction  of  secreting  glands  and  mucous  membranes. 

Secreting  glands.  —  The  secreting  glands  differ  from  other 
glands,  such  as  the  lymphatic  glands,  the  tonsils,  Peyer's 
patches,  etc.,  by  being  always  devoted  to  the  function  of 
secretion,  and  by  discharging  the  secretions  they  form  through 
little  tubes  or  ducts  which  open  exteriorly.  The  lymphatic 
glands  and  bodies  of  allied  structure  are  often  spoken  of  as 
ductless  glands,  in  order  to  distinguish  them  from  these  true 
secreting  glands  provided  with  ducts. 

A  secretion  is  a  substance  elaborated  from  the  blood  by  cell 

142 


CHAP.  XIII.] 


ALIMENTATION. 


143 


action,  and  poured  out  upon  the  external  or  internal  surfaces 
of  the  body.  An  excretion  resembles  a  secretion,  except  that 
whereas  the  secretion  is  formed  to  perform  some  office  in  the 
body,  the  excretion  is  formed  only  to  be  thrown  out  of  the 
body. 

A  secretory  apparatus  consists  essentially  of  a  layer  of  secret- 
ing cells  placed  in  close  communication  with  a  network  of 
blood-vessels.  The  simplest  form  in  which  a  secretory  appa- 


FIG.  93.  — DIAGRAM  SHOWING  THE  VARIOUS  FORMS  OF  SECRETING  STRUCTURES. 
A,  general  plan  of  a  secreting  membrane ;  6,  basement  membrane,  with  cells  (a)  on  one 
side  and  blood-vessels  (c)  on  the  other;  B  and  E,  simple  tubular,  saccular,  and 
coiled  tubular  glands ;  C,  compound  tubular  gland ;  D,  compound  saccular,  or  race- 
mose gland. 

ratus  occurs  is  in  the  shape  of  a  plain,  smooth  surface,  com- 
posed of  a  single  layer  of  epithelial  cells,  resting  usually  on  a 
thin  membrane,  on  the  under  surface  of  which  is  spread  out  a 
close  network  of  blood-vessels.  In  order  to  economize  space 
arid  to  provide  a  more  extensive  secreting  surface,  the  mem- 
brane is  generally  increased  by  dipping  down  and  forming  vari- 
ously shaped  depressions  or  recesses,  these  depressions  or  recesses 
being  called  the  secreting  glands. 

The  secreting  glands  are  of  two  kinds,  simple  and  compound. 
The  simple  glands  are  generally  tubular  or  saccular  cavities,  the 
tube  in  the  tubular  variety  being  sometimes  so  long  that  it  coils 
upon  itself,  as  in  the  sweat  glands  of  the  skin ;  they  all  open 
upon  the  surface  by  a  single  duct.  In  the  compound  glands, 
the  cavities  are  subdivided  into  smaller  tubular  or  saccular 
cavities,  opening  by  small  ducts  into  the  main  duct  which  pours 
the  secretion  upon  the  surface. 

However  simple  or  complicated  the  involuted  surface,  the 
secreting  process  is  essentially  the  same ;  and  in  this  process 
the  nucleated  cells  play  the  most  important  part.  These  cells 
take  into  their  interior  those  substances  from  the  blood  which 
they  require  to  make  the  special  secretion  they  are  set  apart  to 


144  ANATOMY   FOR   NUKSES.          [CHAP.  XIII. 

form,  converting  this  selected  material  into  chemical  com- 
pounds, which  either  act  as  solvents,  as  in  the  digestive  juices, 
or  perform  some  other  office  in  the  body.  The  secretion  the 
cells  elaborate  escapes  from  them  either  by  exudation  or  by  the 
bursting  and  destruction  of  the  cells  themselves.  Cells  filled 
with  secreting  matter  may  also  be  detached  and  carried  out 
entire  with  the  fluid  part  of  the  secretion ;  and,  in  all  cases, 
new  cells  speedily  take  the  place  of  those  which  have  served 
their  office.  The  glands  are  provided  with  lymphatics,  and  fine 
nerve  fibrils  have  also  been  found  to  terminate  in  them.  That 
they  are  under  the  influence  of  the  nervous  system  is  shown  by 
the  fact  that  impressions  made  on  the  nervous  system  affect 
the  secretions,  a  familiar  instance  of  which  is  the  flow  of  saliva 
into  the  mouth,  caused  by  the  sight,  or  smell,  or  even  the 
thought  of  food. 

The  position  and  functions  of  the  several  glands  will  be  de- 
scribed later  in  connection  with  digestion  and  elimination. 

Mucous  membranes.  —  The  mucous  membranes,  unlike  the 
serous  membranes,  line  passages  and  cavities  which  communi- 
cate with  the  exterior.  They  are  all  subject  to  the  contact 
of  foreign  substances  introduced  into  the  body,  such  as  air 
and  food,  and  also  to  the  contact  of  secreted  matters ;  hence 
their  surface  is  coated  over  and  protected  by  mucus,  a  thicker 
and  more  sticky  fluid  than  the  lymph  which  moistens  the 
serous  membranes.  The  mucous  membranes  of  different  parts 
are  continuous,  and  they  may  nearly  all  be  reduced  to  two  great 
divisions ;  namely,  the  gastro-pneumonic  and  the  genito-urinary. 

The  gastro-pneumonic  mucous  membrane  covers  the  inside 
of  the  alimentary  canal,  the  air-passages,  and  the  cavities  com- 
municating with  them.  It  commences  at  the  edges  of  the  lips 
and  nostrils,  proceeds  through  mouth  and  nose  to  the  throat, 
and  thence  is  continued  throughout  the  entire  length  of  the 
alimentary  canal  to  the  anus.  At  its  origin  and  termination 
it  is  continuous  with  the  external  skin.  It  also  extends 
throughout  the  windpipe,  bronchial  tubes,  and  air-sacs.  From 
the  interior  of  the  nose  the  membrane  may  be  said  to  be  pro- 
longed into  the  lachrymal  passages,  and  under  the  name  of 
conjunctival  membrane,  over  the  fore  part  of  the  eyeball  and 
inside  of  the  eyelids,  on  the  edges  of  which  it  again  meets  with 
the  skin.  From  the  upper  part  of  the  pharynx  a  prolongation 


CHAP.  XIII.]  ALIMENTATION.  145 

extends,  on  each  side,  along  the  passage  to  the  ear ;  and  off- 
sets in  the  alimentary  canal  go  to  line  the  salivary,  pancreatic, 
and  biliary  ducts,  and  the  gall-bladder. 

The  genito-urinary  mucous  membrane  lines  the  inside  of  the 
bladder,  and  the  whole  urinary  tract  from  the  interior  of  the 
kidneys  to  the  meatus  urinarius,  or  orifice  of  the  urethra;  it 
also  lines  the  vagina,  uterus,  and  Fallopian  tubes  in  the  female. 

The  mucous  membranes  are  attached  to  the  parts  beneath 
them  by  areolar  tissue,  here  named  "  submucous,"  and  which 
differs  greatly  in  quantity  as  well  as  in  consistency  in  different 
parts.  The  connection  is  in  some  cases  close  and  firm,  as  in 
the  cavity  of  the  nose.  In  other  instances,  especially  in  cavities 
subject  to  frequent  variations  in  capacity,  like  the  gullet  and 
stomach,  it  is  lax ;  and  when  the  cavity  is  narrowed  by  con- 
traction of  its  outer  coats,  the  mucous  membrane  is  thrown  into 
folds  or  rugce  which  disappear  again  when  the  cavity  is  dis- 
tended. But  in  certain  parts  the  mucous  membrane  forms 
permanent  folds  that  cannot  be  effaced,  and  which  project  con- 
spicuously into  the  cavity  which  it  lines.  The  best  marked 
example  of  these  folds  is  seen  in  the  small  intestine,  where 
they  are  called  valvulce  conniventes,  and  which  are  doubtless 
provided  for  increasing  the  amount  of  absorbing  surface  for  the 
products  of  digestion.  The  redness  of  mucous  membranes  is 
due  to  their  abundant  supply  of  blood. 

A  mucous  membrane  is  composed  of  a  layer  of  connective 
tissue  called  the  corium,  and  by  a  layer  of  epithelium  which 
covers  the  surface.  The  epithelium  is  the  most  constant  part  of 
a  mucous  membrane,  being  continued  over  certain  parts  to  which 
the  other  parts  of  the  membrane  cannot  be  traced,  as  over  the 
air-sacs  in  the  lungs,  and  the  front  of  the  cornea  of  the  eye. 
It  may  be  scaly  and  stratified,  as  in  the  throat,  columnar,  as  in 
the  intestine,  or  ciliated,  as  in  the  respiratory  tract.  The 
mucus  which  moistens  its  surface  is  either  derived  from  little 
glands  in  the  mucous  membrane,  or  from  the  columnar  cells 
which  cover  the  surface.  The  corium  of  a  mucous  membrane 
is  composed  of  either  areolar  or  lymphoid  connective  tissue. 
It  is  usually  bounded  next  to  the  epithelium  by  a  basement 
membrane,1  and  next  to  the  submucous  tissue  by  a  thin 

1  A  basement  membrane  is  formed  by  a  layer  of  connective  tissue  cells  joined 
edge  to  edge. 


146 


ANATOMY   FOE,  NURSES.          [CHAP.  XIII 


layer  of  plain  muscular  tissue  termed  the  mmcularis  mucosce'. 
this  layer  is  not  always  present.  The  connective  tissue  layei 
varies  much  in  structure  in  different  parts  ;  the  lymphoid 
variety  is  in  certain  places  greatly  increased  in  amount,  packed 
with  lymphoid  cells,  and  forms  the  solitary  follicles  and 
Peyer's  patches  described  in  Chapter  XII. 

The  small  blood-vessels  conveying  blood  to  the  mucous  mem- 
branes divide  in  the  sub-mucous  tissue,  and  send  smaller  branches 
into  the  corium,  where  they  form  a  network  of  capillaries  just 
under  the  basement  membrane.  The  lym- 
phatics also  form  networks  in  the  corium 
and  communicate  with  larger  vessels  in  the 
sub-mucous  tissue  below.  The  free  surface 
of  the  mucous  membrane  is  in  some  parts 
plain,  but  in  others  is  beset  with  little  emi- 
\OL  nences  named  papillae  and  villi. 

The  papillae  are  best  seen  on  the  tongue  ; 
they  are  small  processes  of  the  corium, 
mostly  of  a  conical  shape,  containing  blood- 
vessels and  nerves,  and  covered  with  epi- 
thelium. 

The  villi  are  most  fully  developed  on  the 
mucous  coat  of  the  small  intestine.     Being 
>     c  ^       set  close   together  like  the  pile  of  velvet, 

FIG.  94.  -AN  INTES-  the^  &ive  a  sha^^   or  villous  appearance 
VILLUS.    a,  a,  a,  to  the  membrane.      They  are  little  projec- 


tions  of  the  mucous  membrane,  covered  with 
c,  c,  longitudinal  muscle  epithelium,    and    containing    blood-vessels 

fibres  ;d,  lacteal  vessel.      au(j    lacteal^    ftnd    are    favourably   arranged 

for  absorbing  nutritive  matters  from  the  intestines. 

SECTION  II.  Food.  —  Under  the  term  "food"  we  include  all 
substances,  solid  or  liquid,  necessary  for  nutrition.  The  ques- 
tion at  once  arises:  What  are  these  substances,  and  how  are 
they  obtained? 

If  we  analyze  the  food  we  daily  take  into  our  mouths  and 
introduce  into  the  alimentary  canal,  we  find  it  separable  into 
two  divisions  ;  viz.  that  which  is  nutritious,  and  that  which 
is  innutritions.  The  nutritious  portion,  that  which  can  be 
digested,  absorbed,  and  made  use  of  by  the  body,  is  generally 
spoken  of  under  the  name  of  food-stuffs  or  food-principles:  the 


CHAP.  XIIL]  ALIMENTATION.  147 

innutritious  portion,  usually  by  far  the  smaller  of  the  two  divis- 
ions, never  enters  the  body  at  all,  properly  speaking,  but  passes 
through  the  alimentary  canal  and  is  excreted  in  the  form  of 
feces. 

Food-stuffs  are  composed  mainly  of  the  elementary  chemical 
substances,  —  oxygen,  carbon,  hydrogen,  nitrogen,  —  and  may, 
according  to  the  varying  proportions  in  which  these  chemical 
elements  combine,  form  five  distinct  and  different  classes  of 
food-stuffs.  These  are :  — 

1.  Proteids. 

2.  Fats. 

3.  Carbo-hydrates. 

4.  Water. 

5.  Saline  or  mineral  matters. 

Proteids.  —  Proteids  form  a  large  proportion  of  all  living 
bodies,  and  are  an  essential  part  of  all  living  structures.  They 
contain  on  an  average  in  every  100  parts  about :  — 

Carbon 53  parts 

Hydrogen 7      " 

Oxygen 24      " 

Nitrogen 16      " 

with  usually  a  little  sulphur  and  sometimes  a  trace  of  phos- 
phorus and  iron.  They  are  the  only  food-stuffs  that  contain 
nitrogen  in  any  appreciable  quantity,  and  are  sometimes 
classed  as  "  nitrogenous "  food-stuffs.  Proteids  occur  in  the 
form  of  albumin  in  the  white  of  egg  (egg-albumin),  in  milk, 
in  blood  and  lymph  (serum-albumin);  in  the  form  of  casein  in 
milk  and  cheese  ;  of  myosin  and  syntonin  in  muscle  ;  of  vitellin  in 
the  yolk  of  eggs ;  of  glutin  in  flour.  Allied  to  proteids  are  the 
chondrin,  obtained  from  cartilage,  and  the  gelatin,  obtained 
from  other  varieties  of  connective  tissue,  by  boiling. 

All  proteids  yield  peptones  very  readily  at  the  temperature 
of  the  body  under  the  action  of  the  acid  gastric,  and  alka- 
line pancreatic  juice.  These  peptones  are  highly  soluble  bodies 
and  readily  absorbed. 

The  foods  that  are  most  rich  in  the  various  forms  of  proteids 
are  meat,  milk,  eggs,  cheese,  all  kinds  of  fish,  wheat,  beans, 
and  oatmeal. 


148  ANATOMY   FOR  NURSES.          [CHAP.  XIII. 

Fats.  —  Fats  are  composed  of  carbon,  hydrogen,  and  oxygen. 
They  contain  on  an  average  in  every  100  parts :  — 

Carbon 76.5  parts 

Hydrogen 12        " 

Oxygen 11.5     " 

The  most  important  fats  are  stearin,  palmatin,  margarin,  and 
olein,  which  exist  in  varying  proportions  in  the  fat  of  animals 
and  vegetable  oils,  and  in  milk,  butter,  lard,  etc.  The  brains  of 
animals  and  the  yolk  of  eggs  contain  a  complex  phosphorized 
fat,  called  lecithin.  Fatty  matters  are  very  abundant  in  olives, 
sweet  almonds,  chocolate,  castor-oil  bean,  hemp,  and  flaxseed. 
Most  of  the  fatty  substances  of  food  are  liquefied  at  the  tem- 
perature of  the  body,  and  are  readily  oxidized,  probably  on 
account  of  the  large  amount  of  carbon  which  they  contain. 

Carbo-hydrates.  —  In  the  carbo-hydrates  there  is  sufficient 
oxygen  present  to  saturate  all  the  hydrogen  and  to  form  water; 
hence  their  name.  In  the  fats,  there  is  not  quite  so  much 
oxygeA  as  hydrogen ;  water  is,  therefore,  not  formed  in  them, 
and  in  this  particular  they  differ  from  the  carbo-hydrates. 

The  carbo-hydrates  contain  in  every  100  parts  about :  — 
». 

Carbon 44  parts 

Hydrogen       ."    \ '   .     .     .       6     ""*• 

Oxygen 50     " 

The  principal  carbo-hydrates  are  starch  and  sugars.  Starch  is 
found  in  wheat,  Indian  corn,  oats,  and  all  grains,  in  potatoes, 
peas,  beans,  roots  and  stems  of  many  plants,  and  in  some  fruits. 
In  a  pure  state,  it  appears  as  a  white  powder,  as  in  arrowroot 
and  cornstarch.  Under  the  influence  of  dry  heat,  starch  may 
be  converted  into  a  soluble  substance,  called  dextrine;  and, 
under  the  action  of  certain  of  the  digestive  juices,  at  the  tem- 
perature of  the  body,  into  sugar.  Of  sugars  there  are  several 
kinds :  cane  sugar  or  sucrose,  obtained  chiefly  from  the  sugar 
cane,  beet  sugar,  and  maple  sugar;  grape  sugar  or  glucose,  found 
in  grapes,  peaches,  and  other  fruits  (it  is  also  readily  manufact- 
ured from  starch) ;  milk  sugar  or  lactose,  obtained  from  milk. 

Carbo-hydrates  are  readily  oxidized ;  together  with  fats,  they 
are  often  classed  as  "  non-nitrogenous  "  food-stuffs. 

Water  is  a  compound  of  oxygen  and  hydrogen,  water  being 


CHAP.  XIII.]  ALIMENTATION.  149 

produced  whenever  two  molecules  of  hydrogen  unite  with  one 
of  oxygen.  Next  to  air,  water  is  the  most  necessary  principle 
of  life.  It  forms  about  seventy  per  cent  of  the  entire  bodily 
weight.  It  is  an  essential  constituent  of  all  the  tissues,  as 
well  as  forming  the  chief  part  of  all  the  fluids  of  the  body. 
It  acts  as  a  solvent  upon  various  ingredients  of  the  food,  lique- 
fying them  and  rendering  them  capable  of  absorption.  Most 
of  the  water  of  the  body  is  taken  into  it  from  without,  but  it  is 
also  formed  within  the  body  by  the  union  of  hydrogen  and 
oxygen  in  the  tissues. 

Mineral  salts.  —  The  mineral  substances  chiefly  necessary  for 
nutrition  are  :  — 

Chloride       i 

Phosphate 

0  ^  f  [ot  soda  and  potash. 

Sulphate 

Carbonate    J 

Phosphate   ~i     _ , . 

~    ,  \  of  lime  and  magnesia. 

Carbonate    J 

Of  these  substances,  chloride  of  soda,  sodium  chloride  or  common 
salt,  is  the  most  important  mineral  ingredient  of  food.  It  is 
contained  in  nearly  everything  we  eat,  but  usually  not  in  suffi- 
cient quantity  to  supply  all  the  needs  of  the  body,  and  we 
therefore  add  it  as  a  separate  article  of  diet.  It  is  present  in 
most  of  the  fluids  of  the  body,  notably  in  the  blood,  the  fluidity 
of  which  it  helps  to  maintain.  The  rest  of  the  mineral  sub- 
stances are  usually  contained  in  sufficient  quantity  in  an  ordi- 
nary diet,  though  occasionally  it  becomes  necessary  to  supply 
them  independently.  Of  all  the  mineral  salts,  phosphate  of  lime 
exists  in  the  largest  quantity  in  the  body ;  it  enters  largely  into 
the  composition  of  the  bones,  teeth,  and  cartilages,  and  gives 
firmness  and  solidity  to  the  tissues.  It  is  present  in  very 
small  quantities  in  the  bodily  fluids,  with  the  exception  of 
milk,  which  contains  a  notable  amount  of  phosphate  of  lime, 
and  which  is  plainly  provided  for  the  ossification  of  the  grow- 
ing bones  of  infants  and  young  children. 

Chemical  composition  of  the  body.  —  Professor  Atwater  gives 
the  following  average  composition  of  the  body  of  man,  weigh- 
ing 148  pounds : — 


150  ANATOMY  FOR  NURSES.         [CHAP.  XIII. 


142.9 


Carbon      
Hvdrosren 

....     31.3 
....     14.6 

Nitrogen       

....       4.6 

Calcium   

.     .     .  '         28    ) 

Phosphorus       .... 

1  4 

Potassium 

34 

Sulphur 

24 

Chlorine  

12 

Sodium    

12 

Magnesium  

04 

Iron 

...               02 

Fluorine  . 

.02 

5.1 


The  human  body,  from  a  chemical  point  of  view,  may  be 
regarded  as  a  compound  of  three  large  classes  of  chemical  sub- 
stances ;  viz.  proteids,  fats,  and  carbo-hydrates  associated  with 
water  and  mineral  salts. 

In  our  first  chapter  we  said  that  protoplasm  was  the  basis  of 
the  life  of  the  body,  and  from  that  point  of  view  we  may  look 
upon  the  human  body  as  an  assemblage  of  variously  modified 
protoplasm.  But  it  comes  to  the  same  thing,  for  the  chemical 
composition  of  protoplasm,  so  far  as  it  has  been  possible  to 
analyze  it,  has  been  found  to  agree  closely  with  that  of  the 
fully  developed  organism. 

The  processes  of  nutrition  that  take  place  in  the  protoplasmic 
cell  are  essentially  the  same  as  those  which  take  place  in  the 
fully  developed  body,  with  this  exception,  that  in  the  one  case  it 
is  a  very  simple,  and  in  the  other  a  very  complex,  process.  In 
both  cases,  non-living  chemical  substances  are  taken  in  from 
without,  and  converted  into  material  which  is  endowed  with 
that  mysterious  property  we  call  life. 

To  support  life,  the  different  food-stuffs  must  be  taken  in 
proper  proportion ;  and,  in  order  that  -all  the  tissues  and  fluids 
of  the  body  may  continue  in  good  condition  and  perform  their 
functions  properly,  they  must  be  supplied  with  all  the  ingredi- 
ents necessary  to  their  constitution.  A  man  may  be  starved  to 
death  at  last  by  depriving  him  of  lime  phosphate  as  surely, 
though  not  as  rapidly,  as  if  he  were  deprived  of  albumin  or  fat. 
Many  a  patient  in  less  well-instructed  times  has  been  slowly 
killed  by  deprivation  of  water,  or  by  exclusive  feeding  on  beef- 
teas  and  jellies. 


CHAP.  XIII.]  ALIMENTATION. 


151 


Average  composition  of  milk,  bread,  and  meat.  —  The  following 

analyses  of  the  composition  of  three  staple  articles  of  diet 

milk,  bread,  and  meat  —  are  taken  from  Dalton. 

Average  composition  of  milk  in  100  parts :  — 

Water 35,4 

Proteids 43 

Sugar 52 

Fat 3.7 

Mineral  salts 4 

Average  composition  of  wheaten  bread  in  100  parts : 

Starchy  matters 56.7 

Proteids 7.0 

Fatty  matters - 1.3 

Mineral  salts 1.0 

Water 34.0 

Average  composition  of  beef  flesh :  — 

Water 77.5 

Proteids 16.0 

Fat 5.0 

Mineral  salts 1.5 

Concluding  remarks.  — The  quantity  and  also  the  kind  of  food 
each  individual  daily  requires  depends  chiefly  upon  the  nature 
and  the  amount  of  the  work  he  is  called  upon  to  perform,  and 
the  conditions  of  the  climate  in  which  he  lives.  Universal 
experience  has  taught  us  that  the  best  sustainers  of  life  are 
milk  and  bread  and  water,  with  a  certain  amount  of  meat  and 
fat.  These  should  form  the  basis  of  all  our  diets,  though  not 
to  the  exclusion  of  other  food-stuffs,  for  it  has  also  been  proved 
that  a  mixed  diet  is  always  to  be  preferred  to  one  that  consists 
constantly  of  the  same  articles  of  food. 

To  determine  the  relative  digestibility  of  foods  is  a  very  diffi- 
cult matter  in  view  of  the  individual  peculiarities  of  different 
people.  Strawberries  may  agree  perfectly  with  ninety-nine 
people,  and  with  the  hundredth,  act  as  a  powerful  poison. 
Some  persons,  as  we  all  know,  cannot  tolerate  milk  or  eggs, 
and  yet,  from  a  chemical  point  of  view,  these  foods  are  emi- 
nently suitable  articles  of  diet. 

The  best  diet  is  that  which  contains  all  the  articles  of  food 


152  ANATOMY   FOR  NURSES.          [CHAP.  XIII. 

necessary  for  the  wants  of  the  body  in  proper  proportions,  which 
is  agreeable  to  the  individual,  and  which  gives  the  minimum 
amount  of  work  to  the  digestive  organs.1 

Food  to  be  of  any  use  to  the  body  must  be  digested  and 
assimilated.  We  may  partake  of  an  ideal  diet  and  yet  remain 
imperfectly  nourished,  if  our  digestive  organs  are  out  of  order, 
or  our  power  to  absorb  and  assimilate  digested  products  in  any 
way  impaired.  In  our  next  chapter  we  shall  describe  the  ali- 
mentary canal,  the  accessory  digestive  organs,  and  the  methods 
by  means  of  which  the  food  is  reduced  to  a  condition  available 
for  the  uses  of  the  body. 

1  For  valuable  information  on  the  relative  value  of  foods  and  preparation  of 
the  same  for  the  sick,  the  student  is  referred  to  Eoland's  "  Handbook  of  Invalid 
Cookery." 


CHAPTER  XIV. 

ALIMENTATION  CONTINUED :   THE  DIGESTIVE  APPARATUS ;   ALI~ 
MENTARY   CANAL,   AND   ACCESSORY  ORGANS. 

THE  digestive  apparatus  consists  of  the  alimentary  canal,  and 
the  accessory  organs,  the  teeth,  salivary  glands,  pancreas,  and 
liver.  By  some  authorities  the  spleen  is  also  now  included 
among  the  digestive  organs.1 

Alimentary  canal.  —  The  alimentary  canal  is  a  musculo-mem- 
branous  tube  extending  from  the  mouth  to  the  anus.  It  is 
about  six  times  the  length  of  the  body,  and  the  greater  part  of 
it  is  coiled  up  in  the  cavity  of  the  abdomen.  The  diameter  of 
the  tube  is  by  no  means  uniform,  being  considerably  dilated  in 
certain  parts  of  its  course.  It  is  composed  of  three  coats  from 
the  mouth  to  where  it  passes  through  the  diaphragm,  and  of 
four  coats  in  the  abdominal  cavity.  These  coats  are :  (1)  the 
mucous ;  (2)  the  sub-mucous  (described  in  our  last  chapter)  ; 
(3)  the  muscular ;  (4)  the  serous.  The  muscular  coat  is  com- 
posed for  the  most  part  of  unstriped  muscular  fibres,  the  layers 
of  which  are  disposed  in  various  ways,  the  most  general  arrange- 
ment being  in  a  longitudinal  and  circular  direction.  By  the 
alternate  contraction  and  relaxation  of  fibres  arranged  in  this 
fashion  (the  contractions  starting  from  above),  the  contents  of 
the  tube  are  propelled  from  above  downwards.  The  serous  coat 
is  derived  from  the  peritoneum,  which  is  the  serous  membrane 
lining  the  walls,  and  covering  the  viscera,  of  the  abdomen. 

Into  the  interior  of  the  alimentary  canal  are  poured  secre- 
tions from  the  glands  in  the  mucous  membrane,  with  which  it  is 
lined,  and  also  secretions  from  the  accessory  glands,  which  lie 
outside  the  canal  and  are  connected  with  its  interior  by  ducts. 

The  alimentary  canal  for  convenience  of  description  may  be 
divided  into :  — 

1  Plate  VII.  shows  relative  position  of  digestive  organs  in  abdominal  cavity. 

153 


PLATE  VII.  —  REGIONS  OF  THE  ABDOMEN  AND  THEIR  CONTENTS  (EDGE  OP  COSTAL 
CARTILAGES  IN  DOTTED  OUTLINE). 


For  convenience  of  description  the  abdomen  may  be  artificially  divided  into  nine 
regions  by  drawing  two  circular  lines  round  the  body  parallel  with  the  cartilages  of 
the  ninth  ribs,  and  the  highest  point  of  the  crests  of  the  ilia ;  and  two  vertical  lines 
from  the  cartilage  of  the  eighth  rib  on  each  side  to  the  centre  of  Poupart's  ligament. 
The  viscera  contained  in  these  different  regions  are  as  follows :  — 


RIGHT  HYPOCHONDRIAC.  — 
The  right  lobe  of  the  liver  and 
the  gall-bladder,  hepatic  flexure 
of  the  colon,  and  part  of  the 
right  kidney. 


EPIGASTRIC  REGION.  —  The 
middle  and  pyloric  end  of  the 
stomach,  left  lobe  of  the  liver, 
the  pancreas,  the  duodenum, 
parts  of  the  kidneys  and  the 
suprarenal  capsules. 


LEFT  HYPOCHONDRIAC. — The 
splenic  end  of  the  stomach,  the 
spleen  and  extremity  of  the  pan- 
creas, the  splenic  flexure  of  the 
colon,  and  part  of  the  left  kid- 
ney. 


RIGHT  LUMBAR.  —  Ascend- 
ing colon,  part  of  the  right  kid- 
ney, and  some  convolutions  of 
the  small  intestines. 


UMBILICAL  REGION.  —  The 
transverse  colon,  part  of  the 
great  omen  um  and  mesentery, 
transverse  part  of  the  duode- 
num, and  some  convolutions  of 
the  jejunum  and  ilium,  and 
part  of  both  kidneys. 


LEFT  LUMBAR.  —  Descending 
colon,  part  of  the  omentum, 
part  of  the  left  kidney,  and 
some  convolutions  of  the  small 
intestines. 


RIGHT  INGUINAL  (ILIAC).  — 
The  ca-cum,  appendix  cifcci. 


HYPOGASTRIC  REGION. — Con- 
volutions of  the  small  intes- 
tines, fix-  bladder  in  children, 
and  in  adults  if  distended,  and 
the  uterus  during  pregnancy. 


LEFT    INGUINAL   (ILIAC).  — 
Sigmoid  flexure  of  the  colon. 


154 


CHAP.  XIV.] 


ALIMENTATION. 


155 


Mouth,  containing  tongue  and  teeth. 

Pharynx. 

(Esophagus. 

Stomach. 

Duodenum. 


Small  intestine 


Jejunum. 


Ilium. 
f  Caecum. 

Large  intestine  j  Colon. 
I  Eectum. 

Mouth  or  buccal  cavity  (vide  Fig.  96).  —  The  mouth  is  a  nearly 
oval-shaped  cavity  with  a  fixed  roof  and  movable  floor.  It  is 
bounded  in  front  by  the  lips,  on  the  sides  by  the  cheeks,  below 
by  the  tongue,  and  above  by  the  palate.  The  palate  con- 
sists of  a  hard  portion 
in  front  formed  by 
bone,  covered  by  mu- 
cous membrane,  and 
cf  a  soft  portion  be- 
hind containing  no 
bone.  The  hard  palate 
forms  the  partition 
between  the  mouth 
and  nose ;  the  soft 
palate  arches  back- 
wards and  hangs  like 
a  curtain  between  the 
mouth  and  the  phar- 
ynx. Hanging  from 
the  middle  of  its  lower 
border  is  a  pointed 
portion  of  the  soft  pal- 
ate called  the  uvula ; 

and  arching  outwards  and  downwards  from  the  base  of  the 
uvula  on  each  side  to  the  roof  of  the  tongue  are  two  curved 
folds  of  muscular  tissue  covered  by  mucous  membrane,  called 
the  pillars  of  the  fauces.  Just  before  reaching  the  tongue, 
the  two  pillars,  on  either  side,  are  separated  by  a  triangular 
space  in  which  lie  the  small  masses  of  lymphoid  tissue  called 
the  tonsils.  The  fauces  is  the  name  given  to  the  aper- 


FIG.  95.  —  THE  SALIVARY  GLANDS. 


156  ANATOMY   FOR   N  URSES.  [CHAP.  XIV. 

ture  leading  from  the  mouth  into  the  pharynx  or  throat 
cavity. 

The  mucous  membrane  lining  the  mouth  contains  many 
minute  glands  which  pour  their  secretion  upon  its  surface,  but 
the  chief  secretion  of  the  mouth  is  supplied  by  the  salivary 
glands,  which  are  three  pairs  of  large  compound  saccular  glands 1 
called  the  parotid,  submaxillary,  and  sublingual,  respectively. 
Each  parotid  gland  is  placed  just  in  front  of  the  ear,  and  its  duct 
passes  forwards  along  the  cheek,  until  it  opens  into  the  interior 
of  the  mouth  opposite  the  second  upper  molar. 

The  submaxillary  and  sublingual  glands  are  situated  below 
the  jaw  and  under  the  tongue,  the  submaxillary  being  placed 
further  back  than  the  sublingual.  Their  ducts  open  in  the 
floor  of  the  mouth  beneath  the  tongue.  The  secretion  of  these 
salivary  glands,  mixed  with  that  of  the  small  glands  of  the 
mouth,  is  called  saliva. 

The  tongue.  —  The  tongue  is  a  freely  movable  muscular  organ 
attached  by  its  base  to  the  hyoid  bone.  Besides  being  the 
special  seat  of  the  sense  of  taste,  it  is  a  useful  aid  in  mastication 
and  deglutition.2 

The  teeth.  —  The  semicircular  borders  of  the  upper  and  lower 
jaw-bones  (the  alveolar  processes)  contain  thirty-two  sockets  for 
the  reception  of  the  teeth  ;  extending  over  the  bones  and  a  little 
way  into  each  socket  is  a  dense  insensitive  fibrous  tissue  covered 
by  smooth  mucous  membrane,  the  gums. 

There  are  two  sets  of  teeth  developed  during  life :  the  first 
or  milk  teeth,  and  the  second  or  permanent  teeth.  The  cutting 
of  the  milk  teeth  begins  usually  at  six  months  and  ends  with 
the  second  year ;  there  are  only  twenty  of  these  teeth,  and  they 
are  replaced  during  childhood  by  the  permanent  teeth.3 

Each  tooth  consists  of  two  portions,  the  crown  and  the  fang : 
the  crown  projects  into  the  cavity  of  the  mouth,  the  fang  is 
embedded  in  the  socket.  According  to  their  shape  and  the  use 
teetli  are  divided  into  incisors,  canines,  bicuspids,  and  molars. 

1  For  description  of  compound  glands  see  Section  I.  Chapter  XIV. 

2  A  detailed  description  of  the  tongue  will  be  found  in  the  chapter  on  the 
organs  of  special  sense. 

a  The  milk  teeth  are  usually  cut  in  the  following  order,  the  teeth  appearing 
first  in  the  lower  jaw:  central  incisors,  7th  month  ;  lateral  incisors,  7th  to  10th 
month ;  front  molars,  12th  to  14th  month  ;  canine,  14th  to  20th  month  ;  back 
molars,  18th  to  36th  month. 


CHAP.  XIV.] 


ALIMENTATION. 


157 


Beginning  in  the  middle  line  of  each  jaw  and  counting  from 

before    backwards,  there    are  four  incisors,  two   canines,  four 

bicuspids,  and  six  molars  in  the  upper  and  in  the  lower  jaw. 

The  incisors  have  wide  sharp  edges,  and  are  specially  adapted 

for  cutting  the  food  ;  the  canines,  or  eye  teeth,  have  a  sharp 

pointed   edge,  are  longer  than  the  incisors,  and  are  specially 

useful  for  tearing  food  asunder, 

or,    as    in    dogs    and    other   car- 

nivora,  for  holding    prey.      The 

bicuspids,  or  false   grinders,  are 

broader,  with  two  points  or  cusps 

on  each  crown  :  these  teeth  have 

only  one  fang,  the  fang,  however, 

being  more    or    less   completely 

divided  into  two.      The  molars, 

or    true     grinders,    have     broad 

crowns   with   small  pointed  pro- 

jections, which  make  them  well 

fitted  for  crushing  and  bruising 

the  food  :  they  each  have  two  or 

three  fangs.     The  twelve  molars 

do  not  replace  the  milk  teeth,  but 

are    gradually   added    with    the 

extension  of  the  jaws,  the  last  or 

hindermost  molars  not  appearing 

until  twenty-one   years   of   age: 


777, 


FlG.  «,._!„,,  MOUTH,  NOSE 

they   are     often     on   this   account     PHARYNX,  WITH  THE  LAKYNX  AND 

"wisdom  fppth  " 
Cl1' 

The 


COMMENCEMENT  OF  GULLET,   SEEN 
IN  SECTION,    a,  vertebral  column  ;  6, 


teeth     are      composed     of      gullet;  c,  trachea;  d,  larynx;  e,  epi- 

three    bone-like  tissues,   enamel,    tt'&'XEfSttZ 

dentine,  and    cement;    these   Sub-     fauces;  <?,  opening  of  Eustachian  tube; 
-•1    -i       j        ,-1          i  h,  nasal  cavity;    k,  tongue;    /,  hard 

stances  are  all  harder  than  bone,    palate;  m>  sphenoid  bone  at  base  of 

enamel  being  the  hardest  tissue  skull;  n,  roof  of  nasal  cavity  ;  o,p,  q, 
j,  ,.  ,,  ,,  T  j  i  -A  placed  in  nasal  cavity. 

found  in  the  body.     In  the  inte- 

rior of  each  tooth  is  a  cavity,  the  pulp-cavity,  which  is  filled 
with  a  highly  vascular  and  nervous  tissue  called  the  dental  pulp. 
The  teeth  are  developed  from  epithelium  in  much  the  same  way 
as  the  hairs;  for  description  of  which  see  page  192. 

The  pharynx.  —  The  pharynx  or  throat  cavity  is  a  musculo- 
membranous  bag,  shaped  somewhat  like  a  cone,  with  its  broad 


158  ANATOMY   FOR  NUKSES.  [CHAP.  XIV. 

end  turned  upwards,  and  its  constricted  end  downwards  to 
end  in  the  O3sophagus.  It  is  about  four  and  a  half  inches 
long,  and  lies  behind  the  nose,  mouth,  and  larynx.  Above,  it 
is  connected  with  the  base  of  the  skull,  and  behind,  with  the 
cervical  vertebrae ;  in  front  and  on  each  side  are  apertures 
which  communicate  with  the  nose,  ears,  mouth,  and  larynx. 

Of  these  apertures  there  are  seven :  two  in  front  above,  lead- 
ing into  the  back  of  the  nose,  the  posterior  nares ;  two,  one  on 
either  side  above,  leading  into  the  Eustachiari  tubes,  which  com- 
municate with  the  ears ;  one  midway  in  front,  the  fauces ;  and 
two  below,  one  opening  into  the  larynx  and  the  other  into  the 
oesophagus.  The  mucous  membrane  lining  the  pharynx  is  well 
supplied  with  glands,  and  at  the  back  of  the  cavity  there  is  a 
considerable  mass  of  lymphoid  tissue.  The  muscular  tissue  in 
the  walls  of  the  pharynx  is  of  the  striped  variety,  and  when  the 
act  of  swallowing  is  about  to  be  performed  the  muscles  draw 
the  pharyngeal  bag  upwards  and  dilate  it  to  receive  the  food ; 
they  then  relax,  the  bag  sinks,  and  other  muscles  contracting 
upon  the  food,  it  is  pressed  downwards  and  onwards  into  the 
oesophagus. 

The  oesophagus  or  gullet.  —  The  oesophagus  is  a  comparatively 
straight  tube,  about  nine  inches  long,  extending  from  the 
pharynx,  behind  the  trachea,  and  through  the  diaphragm,  to 
its  termination  in  the  upper  or  cardiac  end  of  the  stomach. 
The  muscular  fibres  in  the  walls  of  the  oesophagus  are  arranged 
in  an  external  longitudinal  and  in  an  internal  circular  layer. 
The  mucous  membrane  is  disposed  in  longitudinal  folds  which 
disappear  upon  distension  of  the  tube.  The  mucous  mem- 
brane in  the  mouth,  pharynx,  and  oesophagus  is  covered  for 
the  most  part  by  stratified  epithelium. 

The  stomach.  —  The  stomach  is  the  most  dilated  portion  of 
the  alimentary  canal.  It  is  curved  upon  itself,  so  that  below  it 
presents  a  long,  rounded  outline,  called  the  greater  curvature, 
and  above  a  constricted,  concave  outline,  called  the  lesser 
curvature. 

It  is  placed  transversely  in  the  abdominal  cavity,  immediately 
beneath  the  diaphragm,  the  larger  expanded  end  lying  in  con- 
tact with  the  spleen,  and  the  smaller  end  under  the  liver.  The 
stomach  has  necessarily  two  openings :  the  one  leading  into  the 
oesophagus  is  usually  termed  the  cardiac  aperture;  the  other, 


CHAP.  XIV.]  ALIMENTATION.  159 

leading  into  the  small  intestine,  the  pyloric.  The  pyloric  aper- 
ture is  guarded  by  a  kind  of  valve  composed  of  circular  mus- 
cular fibres,  which  form  a  constricted  ring  projecting  into  the 
pyloric  opening.  By  this  arrangement,  the  food  is  kept  in 
the  stomach  until  it  is  ready  for  intestinal  digestion,  when  the 
circular  fibres  relax  and  allow  it  to  pass. 

When  moderately  distended,  the  stomach  measures  about 
four  inches  vertically  and  twelve  inches  from  side  to  side.  It 
has  four  coats.  The^  outer  serous  coat  is  formed  by  a  fold  of 
the  peritoneum.  The  fold  is  slung  over  the  stomach,  in 
much  the  same  way  as 
we  sling  a  towel  over  a 
clothes-line,  and  covers  it 
before  and  behind.  The 
anterior  and  posterior 
folds  unite  at  the  lower 
border  of  the  stomach 
and  form  an  apron-like 
appendage,  the  omentum, 
which  covers  the  whole 
of  the  intestines.  The 
omentum  often  contains 
a  large  amount  of  fat.  FlG  97._VERTICAL  AND  LoNGITUDINAL  SEC- 

The    muscular    COat    of    TION  OF  STOMACH  AND  DUODENUM.    1,  cesopha- 
i-t  i  '   i          r    gus,  on  its  internal  surface  the  folds  or  ruga?  of 

the   stomach   consists    of  fhe  mucous  membrane  are  shown;  2>  c{Trd5ac 

three  layers  of   UHStriped    orifice  of  stomach ;  5,  lesser  curvature ;  <>,  greater 
-,       ,.  curvature;   8,  rugae  in   interior   of  stomach;   9, 

muscular  tissue:  an  outer,   pyloric  orifice;  10>  n>  13>  interior  of  duodenum 

formed  of  longitudinal  showing  valvulre  conniventes ;  12,  duct  conveying 
£,  .,  ,,  ,.  the  bile  and  pancreatic  juice  into  duodenum;  15, 

fibres ;     a   middle,    OI    Cir-    commencement  of  jejunum. 

cular;    and  an  inner,   of 

less  well-developed,  obliquely  disposed  fibres.  The  alternate 
contraction  and  relaxation  of  these  fibres  causes  the  food  to 
be  carried  round  and  round  the  stomach,  and  at  the  same  time, 
subjects  it  to  considerable  pressure. 

The  mucous  membrane  is  very  soft  and  thick,  the  thickness 
being  mainly  due  to  the  fact  that  it  is  densely  packed  with  small 
tubular  glands;  it  is  covered  with  columnar  epithelium,  and  in 
its  un distended  condition  is  thrown  into  folds  or  rugae.  The 
surface  is  honeycombed  with  tiny  shallow  pits,  into  which  the 
ducts  or  mouths  of  the  tubular  glands  open.  The  glands  are 


160 


ANATOMY  FOR  NURSES. 


[CHAP.  XIV. 


of  two  kinds,  and  secrete  mucus,  and  the  special  secretion  of 
the  stomach,  the  gastric  juice.  The  stomach  is  supplied  with 
nerves  from  the  sympathetic  system,  and  also  with  branches 
from  the  pneumogastric  nerve,  which  comes  from  the  cerebro- 
spinal  system. 

The  small  intestine.  —  The  small  intestine  fills  the  greater 
part  of  the  front  of  the  abdominal  cavity.  It  is  about  twenty 
feet  long,  two  inches  wide  at  its  gastric  end,  and  narrows  to 
nearly  one  and  a  quarter  inches  where  it 
joins  the  large  intestine.  The  small  intes- 
tine is  divided  by  anatomists  into  three 
portions.  The  first  ten  or  twelve  inches 
is  called  the  duodenum  ;  the  succeeding 
two-fifths,  the  jejunum;  and  the  rest,  the 
ilium.  The  intestines  are  invested  by  a 
fold  of  the  peritoneum  in  much  the  same 
way  as  the  stomach.  In  this  situation,  the 
fold  of  the  peritoneum  is  called  the  me- 
sentery, and  between  its  two  layers  are 
numerous  blood-vessels,  lymphatics,  and 
lymphatic  glands. 

The  muscular  coat  of  the  small  intestine 
has  only  two  layers  :  an  outer,  thinner  and 
longitudinal;  and  an  inner,  thicker  and 

.    6 

circular. 

xhe  mucous  coat  is  highly  developed.    In 


ved 


FIG.  98.  —  AN  INTES- 

TINAL  VILLUS.    a,  a,  a, 
columnar      epithelium; 

6,  6,  capillary  network;  ...       -,  i        . 

c,  c,  lymphoid  tissue  the  tirst  place  it  is  largely  increased  by 
fibfeS;  *'  bein£  arrange<l  in  permanent  folds,  the 
valvulse  conniventes  (vide  Fig.  97),  which 
project  transversely  into  the  interior  of  the  tube.  The  onward 
course  of  the  food  is  delayed  by  being  caught  in  the  hollows 
formed  by  these  folds,  and  thus  more  thoroughly  subjected  to 
the  action  of  the  digestive  juices  :  this  arrangement  also  affords 
a  larger  surface  for  absorption.  The  valvulse  conniventes  are 
not  found  in  the  beginning  of  the  duodenum,  but  begin  to 
appear  one  or  two  inches  from  the  pylorus  ;  about  the  middle 
of  the  jejunum  they  begin  to  decrease  in  size,  and  in  the  lower 
part  of  the  ilium  they  almost  entirely  disappear. 

Again,  the  surface  of  the  mucous  membrane  is  increased  by 
the  finger-like  projections  which  are  so  close  set  as  to  give  a 


CHAP.  XIV.] 


ALIMENTATION. 


161 


snaggy  or  velvety  appearance  to  the  membrane.  These  projec- 
tions or  villi,  as  they  are  termed,  extend  throughout  the  whole 
length  of  the  small  intestine,  and  are  especially  provided  for 
purposes  of  absorption.  Each  villus  is  a  portion  of  the  mucous 
membrane,  and  consists  of  an  external  layer  of  columnar  cells 
attached  to  a  basement  membrane,  and  a  central  mass  of  lym- 
phoid  tissue.  In  the  centre  of  each  villus  is  the  rootlet  of  a 
lacteal  vessel,  while  under  the  basement  membrane  is  a  network 
of  capillaries.  The  blood-vessels  and  lymphatics  of  the  villi 
communicate  with  networks  of  both  vessels  in  the  sub-mucous 
coat  below.  Besides  these  projections  formed  for  absorption, 


FIG.  99.  —  SECTION  THROUGH  THE  LYMPHOID  TISSUE  OF  A  SOLITARY  GLAND. 
(Cadiat.)  a,  centre  of  the  gland,  with  the  lymphoid  tissue  fallen  away;  6,  epithe- 
lium of  mucous  membrane ;  c,  c,  villi,  with  epithelium  partly  broken  away ;  d,  crypts, 
or  glands,  of  Lieberkiihn. 

the  mucous  membrane  is  thickly  studded  with  secretory  glands  ; 
the  larger  number  of  these,  found  all  over  the  surface  of  the 
intestine,  are  called  the  glands  or  crypts  of  Lieberkiihn,  while  a 
smaller  number,  found  chiefly  in  the  duodenum,  are  named  the 
duodenal  or  Brunner's  glands.  These  glands  are  supposed  to 
secrete  the  intestinal  juice,  succus  entericus. 

Again,  in  the  corium  of  the  mucous  coat  the  lymphoid  tissue 
is  collected  into  numerous  solitary  glands  or  follicles,  and  into 
groups  of  glands,  the  Peyer's  patches,  the  functions  of  which 
are  not  yet  clearly  understood. 


162  ANATOMY   FOR  NURSES.          [CHAP.  XIV. 

The  large  intestine.  —  The  large  intestine  is  about  five  feet 
long,  and  from  two  and  a  half  to  one  and  a  half  inches  wide  ; 
it  extends  from  the  ilium  to  the  anus.  It  is  divided  into  the 
csecum,  with  the  vermiform  appendix,  the  colon,  and  the  rectum. 
The  coBcum  (ccecus,  blind)  is  a  large  blind  pouch  at  the  com- 
mencement of  the  large  intestine.  The  small  intestine  opens 
into  the  side  wall  of  the  large  intestine  about  two  and  a  half 
inches  above  its  —  the  large  intestine's  —  commencement,  the 
caecum  forming  a  cul-de-sac  below  the  opening.  Attached  to 
the  lower  end  of  the  csecum  is  a  narrow, 
worm-like  tube  about  the  size  of  a  lead- 
pencil,  the  vermiform  appendix.  The 
csecum  and  appendix  lie  just  beneath 
the  front  abdominal  wall  in  the  right 
iliac  region  (vide  Plate  VII.).  The  open- 
ing from  the  ilium  into  the  large  intes- 
tine is  provided  with  two  large  project- 
ing lips  of  mucous  membrane  which 
allow  the  passage  of  material  into  the 
large  intestine,  but  effectually  prevent 
the  passage  of  material  in  the  opposite 
direction.  These  mucous  folds  form 
what  is  known  as  the  ilio-csecal  valve. 

FIG.  100.  —  C^CUM,  SHOW- 
ING ITS  APPENDIX,  ENTRANCE        The  colon  may  be  subdivided  into  the 

vUTVc'aLmT^Tom1:  ascending,  transverse,  and  descending 
mencement  of  colon;  3,  en-  colon,  and  the  sigmoid  flexure.  The 
E£2£  4.  ^."^  ending  portion  runs  up  on  the  right 
6,  aperture  of  vermiform  ap-  side  of  the  abdomen  until  it  reaches 

•rmappen. 


left,  and  is  continued  straight  across  the  abdomen  as  the  trans- 
verse colon  until,  reaching  the  left  side,  it  turns  abruptly  and 
passes  downwards  as  the  descending  colon.  Reaching  the  left 
iliac  region  on  a  level  with  the  margin  of  the  crest  of  the  ilium, 
it  makes  a  curve  like  the  letter  S,  —  hence  its  name  of  sigmoid 
flexure,  —  and  finally  ends  in  the  rectum.  The  rectum  is  from 
six  to  eight  inches  long  ;  it  passes  obliquely  from  the  left  until 
it  reaches  the  middle  of  the  sacrum,  then  it  follows  the  curve 
of  the  sacrum  and  coccyx,  and  finally  arches  slightly  backwards 
to  its  termination  at  the  anus.  The  anal  opening  is  guarded 
by  two  circular  muscles  called,  respectively,  the  internal  and 
external  sphincters. 


CHAP.  XIV.]  ALIMENTATION.  163 

The  large  intestine  has  the  usual  four  coats,  except  near  its 
termination,  where  the  serous  is  wanting.  The  muscular  coat, 
along  the  caecum  and  colon,  has  a  peculiar  arrangement.  The 
longitudinal  fibres  are  gathered  up  in  three  thick  bands,  and 
these  bands,  being  shorter  than  the  rest  of  the  tube,  the  walls  are 
puckered  between  them.  The  mucous  coat  possesses  no  villi  or 
valvulae  conniventes,  but  is  usually  thrown  into  effaceable 
folds,  somewhat  like  those  of  the  stomach.  It  contains  nu- 
merous glands,  resembling  the  crypts  of  Lieberkiihn  found  in 
the  small  intestine. 

Accessory  organs  of  digestion.  —  The  accessory  organs  of  diges- 
tion are,  the  teeth  and  salivary  glands  (which  have  already 
been  sufficiently  described),  the  pancreas,  and  the  liver. 

The  pancreas.  —  The  pancreas  is  a  compound,  secreting  gland, 


FIG.  101. — POSTERIOR  VIEW  OF  PANCREAS.  1,  pancreas;  2,  pancreatic  duct;  6, 
opening  of  common  duct,  formed  by  union  of  pancreatic  and  choledochus  ducts,  into 
duodenum;  A,  pyloric  end  of  stomach;  B,  duodenum ;  C,  part  of  gall-bladder;  D, 
cystic  duct ;  E,  hepatic  duct ;  F,  choledochus  duct. 

closely  resembling  the  salivary  glands  in  structure,  except  that 
the  secreting  cavities  are  saccular  in  the  salivary  glands,  and 
more  distinctly  tubular  in  the  pancreas.  The  cavities  are 
grouped  in  lobules,  each  lobule  having  its  own  duct.  The 
lobules  are  joined  together  by  connective  tissue  to  form  lobes, 
and  the  lobes,  united  in  the  same  manner,  form  the  gland. 
The  small  ducts  open  into  one  main  duct,  which,  running 
lengthwise  through  the  gland,  pierces  the  coats  of  the  duo- 


164  ANATOMY  FOE  NTJBSES.          [CHAP.  XIV. 

denura  and  pours  its  contents  into  the  interior  of  the  intestine. 
The  secretion  formed  in  the  pancreas  is  called  the  pancreatic 
juice. 

In  shape,  the  pancreas  somewhat  resembles  a  dog's  tongue. 
It  is  a  flat,  elongated  organ,  about  six  to  eight  inches  in  length, 
one  and  a  half  inches  in  width,  and  from  half  an  inch  to  an  inch 
thick.  It  lies  beneath  the  greater  curvature  of  the  stomach  and 
at  the  back  of  the  abdominal  cavity. 

The  liver.  —  The  liver  is  the  largest  gland  in  the  body,  weigh- 
ing ordinarily  from  fifty  to  sixty  ounces,  and  measuring  ten  to 

twelve  inches  from  side 
to  side,  six  to  seven  from 
above  downwards,  and 
three  inches  from  before 
backwards  in  its  thickest 
part.  It  is  a  dark  red- 
dish-brown organ,  placed 
in  the  upper  right  and 
middle  portion  of  the 
abdomen,  and  extending 

somewhat  into  the   left 
FIG.    102. —UNDER    SURFACE    OF    LIVER.     1, 

right  lobe ;  2,  left  lobe ;  3,  4,  5,  smaller  lobes ;  9, 12,  hypochondriac       region, 

inferior  vena  cava ;  10,  gall-bladder ;  11,  transverse  rpi        llrkrkOT>   nrmArov    c 

fissure,  or  "  gate  of  liver,"  containing  bile  duct,  he-  UPP6 

patic  artery,  and  portal  vein.  face  fits  closely  into  the 

under    surface    of    the 

diaphragm.  The  under  concave  surface  of  the  organ  fits  over 
the  right  kidney,  the  upper  portion  of  the  ascending  colon,  and 
the  pyloric  end  of  the  stomach.  The  liver  is  unequally  divided 
into  two  lobes,  the  right  being  much  larger  than  the  left.  It  is 
covered  by  a  layer  of  peritoneum,  and  is  also  suspended  and 
kept  in  position  by  ligamentous  peritoneal  bands. 

The  liver  not  only  differs  in  size  from  the  other  secreting 
glands ;  it  also  offers  other  striking  peculiarities.  First,  it  re- 
ceives its  supply  of  blood  from  two  different  sources ;  namely, 
arterial  blood  from  the  hypatic  artery,  and  venous  blood  from 
the  stomach,  spleen,  pancreas,  and  intestines,  by  means  of  the 
portal  vein.  Secondly,  the  different  parts  of  the  secretory 
apparatus,  the  cells,  blood-vessels,  and  ducts,  instead  of  being 
arranged  as  elsewhere  in  distinct  tubes  or  sacs,  are  closely 
united  and  massed  together.  The  secreting  cells  are  collected 


CHAP.  XIV.]  ALIMENTATION.  165 

into  small  polyhedral  or  many-sided  masses,  called  hepatic 
lobules;  the  blood-vessels  form  networks  around  and  in  the 
lobules ;  while  the  ducts  which  carry  away  the  secretion  (bile) 
begin  within  the  lobules  in  the  form  of  tiny  channels,  running 
between  the  cells. 

The  whole  liver  is  invested  in  an  envelope  or  capsule  of  con- 
nective tissue  (Glisson's  capsule),  and  the  lobules  are  divided 
from  one  another  by  very  delicate  partitions  of  areolar  tissue, 
each  lobule  being  about  the  size  of  a  pin's  head  and  filled  with 
the  special  liver  cells. 

The  large  portal  vein  and  the  small  hepatic  artery  enter  the 


FIG.  103. — DIAGRAMMATIC  REPRESENTATION  OF  Two  HEPATIC  LOBULES.  The 
left  hand  lobule  is  represented  with  the  intralobular  vein  cut  across;  in  the  right 
hand  one  the  section  takes  the  course  of  the  intralobular  vein,  p,  interlobular 
branches  of  the  portal  vein;  h,  intralobular  branches  of  the  hepatic  veins;  s,  sub- 
lobular  vein ;  e,  capillaries  of  the  lobules.  The  arrows  indicate  the  direction  of  the 
course  of  the  blood.  The  liver-cells  are  only  represented  in  one  part  of  each  lobule. 

liver  together  on  its  under  surface  at  what  is  called  the  "  gate 
of  the  liver,"  the  bile  duct  passing  out  at  the  same  place.  The 
branches  of  these  three  vessels,  enclosed  by  loose  connective 
tissue,  in  which  are  lymphatics  and  nerves,  accompany  one 
another  in  their  course  through  the  organ.  The  smallest 
branches  penetrate  between  the  lobules,  and,  surrounding  and 
lying  between  each  lobule,  are  known  as  the  interlobular 
branches.  From  the  interlobular  branches  of  the  portal  vein, 
thus  surrounding  the  circumference  of  each  lobule,  run  capillary 
vessels,  somewhat  like  the  spokes  of  a  wheel.  These  capillaries, 
converging  towards  the  centre,  merge  into  a  veinlet,  the  intra- 


166 


ANATOMY   FOR,   NURSES.  [CHAP.  XIV. 


lobnlar  vein,  which,  running  down  the  middle  of  the  lobule, 
empties  into  a  vein  at  its  base.  This  vein,  lying  at  the  base  of 
each  lobule,  is  called  the  sublobular  vein,  and  empties  its  con- 
tents into  the  hepatic  veins,  by  means  of  which  the  blood  is 
conveyed  from  the  back  of  the  liver  into  the  inferior  vena  cava. 


FIG.  104.  —  LOBULE  OF  RABBIT'S  LIVKR,  VESSELS  AND    BILE  DUCTS   INJECTED. 
a,  central  or  intralobular  vein  ;  b,  b,  interlobular  veins;  c,  interlobular  bile  duct. 

Thus  each  lobule  is  a  mass  of  hepatic  cells,  pierced  everywhere 
with  a  network  of  blood  capillaries. 

The  bile  ducts  commence  between  the  hepatic  cells  in  the 
form  of  fine  canaliculi  lying1  between  the  adjacent  sides  of  two 
cells  and  forming  a  close  network,  the  meshes  of  which  corre- 
spond in  si'/.t;  to  the  cells.  At  the  circumference  of  the  lobules, 


CHAP.  XIV.]  ALIMENTATION. 

these  fine  canaliculi  pass  into  the  interlobular  bile  ducts  which, 
running  in  connection  with  the  blood-vessels,  finally  empty  into 
the  two  bile  ducts  which  leave  the  liver  at  the  opening,  spoken 
of  above  as  the  "  gate  of  the  liver." 

The  cells  of  the  liver  manufacture  bile  from  the  blood,  and 
discharge  this  into  the  minute  bile  canaliculi,  whence  it  passes 
into  the  bile  ducts  to  be  conveyed  into  the  small  intestine. 
The  cells,  however,  perform  another  important  function,  in  that 
they  change  some  of  the  substances  brought  to  them  in  the 
blood  from  the  digestive  organs  in  such  a  manner  as  to  render 
these  substances  suitable  for  the  nutrition  of  the  body ;  but,  at 
present  it  will  be  enough  to  consider  the  secretion  of  bile  as 
the  only  function  of  the  liver. 

The  bile  is  taken  from  the  liver  by  a  right  and  left  duct, 
which  soon  unite  to  form  the  hepatic  duct.  The  hepatic  duct 
runs  downward  and  to  the  right  for  an  inch  and  a  half,  and 
then  joins  at  an  acute  angle  the  duct  from  the  gall-bladder, 
termed  the  cystic  duct.  The  hepatic  and  cystic  ducts  together 
form  the  common  bile  duct  (ductus  communis  choledochus), 
which  runs  downwards  for  about  three  inches,  and  enters  the 
duodenum  at  the  same  opening  as  the  pancreatic  duct. 

The  gall-bladder  (vide  Fig.  102)  is  a  pear-shaped  sac,  lodged 
in  a  depression  on  the  under  surface  of  the  right  lobe  of  the 
liver.  It  is  lined  by  columnar  epithelium,  and  its  walls  are 
formed  of  fibrous  and  muscular  tissue.  It  is  held  in  position 
by  the  peritoneum,  and  serves  as  a  reservoir  for  the  bile.  Dur- 
ing digestion  the  bile  is  poured  steadily  into  the  intestine ;  in 
the  intervals  it  is  stored  in  the  gall-bladder. 

To  recapitulate :  the  digestive  apparatus  may  be  said  to  con- 
sist of  a  tube  and  of  important  accessory  organs  placed  in  close 
connection  and  communication  with  it.  For  convenience  of 
description,  the  tube  may  be  divided  in  sections,  each  of  which 
is  furnished  with  mechanical  and  chemical  appliances  for  reduc- 
ing the  food  into  a  soluble  condition.  First,  the  mouth  cavity, 
which  is  provided  with  muscular  cheeks  and  movable  jaw, 
tongue,  teeth,  and  the  chemical  solvent,  saliva,  secreted  by  the 
salivary  glands ;  secondly,  the  two  passages,  the  pharynx  and 
oesophagus,  serving  to  convey  the  food  into  the  next  section, 
the  stomach,  which  is  furnished  with  muscular  walls  for  crush- 
ing and  churning  the  food,  and  with  glands  to  secrete  the  acid 


108  ANATOMY   FOR   NURSES.          [CHAP.  XIV. 

digestive  solvent,  the  gastric  juice ;  thirdly,  the  small  intestine, 
supplied  with  bile  and  pancreatic  juice,  and  with  a  highly 
specialized  mucous  membrane  adapted  to  both  digestive  and 
absorptive  purposes;  and  lastly,  the  large  intestine,  having 
feeble  digestive  properties,  but  serving  to  absorb  all  the  nutri- 
tious portion  of  the  food  still  remaining,  and  to  pass  the  residue 
onwards  to  be  finally  thrown  out  of  the  body  in  the  form  of 
feces. 


CHAPTER  XV. 

ALIMENTATION  CONCLUDED:  DIGESTION;  CHANGES  THE  FOOD 
UNDERGOES  IN  THE  MOUTH,  STOMACH,  SMALL  AND  LARGE 
INTESTINE;  SUMMARY  OF  DIGESTION;  ABSORPTION. 

Digestion.  —  Digestion  is  the  process  by  means  of  which  the 
food  we  take  into  our  mouths  is  transformed  into  a  condition 
of  solution  or  emulsion  suitable  for  absorption  into  the  blood. 
This  transformation  is  rapid  or  gradual  according  to  the  nature 
of  the  food-stuffs  the  digestive  solvents  are  called  upon  to  dis- 
solve. We  all  know  practically,  for  instance,  that  it  takes  much 
longer  to  digest  a  piece  of  beefsteak  than  a  cup  of  bouillon,  and 
that  when  we  wish  to  save  the  digestive  powers  as  much  as  pos- 
sible we  place  a  person  upon  "  liquid  diet." 

Remembering  that  the  three  solid  food-stuffs  are  proteids, 
fats,  and  carbohydrates,  we  will  proceed  to  describe  how  each 
of  these  is  transformed  into  a  soluble  condition  in  its  course 
through  the  alimentary  canal. 

Changes  the  food  undergoes  in  the  mouth ;  mastication  and 
deglutition.  —  When  solid  food  is  taken  into  the  mouth  it  is  cut 
and  ground  by  the  teeth,  being  pushed  between  them  again  and 
again  by  the  muscular  contractions  of  the  cheeks  and  the  move- 
ments of  the  tongue  until  the  whole  is  thoroughly  crushed  and 
ground  down.  During  this  process  of  mastication  the  salivary 
glands  are  excited  to  very  active  secretion,  the  saliva  is  poured 
in  large  quantities  into  the  mouth,  and  mixing  with  the  food 
moistens  it  and  reduces  it  to  a  soft  pulpy  condition.  A  certain 
amount  of  air  caught  in  the  bubbles  of  the  saliva  also  becomes 
entangled  in  the  food. 

The  food  thus  softened  and  moistened  is  collected  from  every 
part  of  the  mouth  by  the  movements  of  the  tongue,  brought 
together  upon  its  upper  surface,  and  then  pressed  backwards 

169 


170  ANATOMY   FOE,  NURSES.  [CHAP.  XV. 

through  the  fauces  into  the  pharynx.  The  elevation  of  the 
soft  palate  prevents  the  entrance  of  food  into  the  nasal  cham- 
bers, while  the  epiglottis  bars  its  entrance  into  the  air  passages, 
and  it  is  guided  safely  and  rapidly  through  the  pharynx  into  the 
oesophagus.  Here  it  passes  beyond  the  control  of  the  will ;  it 
is  grasped  by  the  oesophageal  muscles  and  by  a  continuous  and 
rapid  peristaltic  action  is  carried  onwards  and  downwards  into 
the  stomach. 

Saliva.  —  Mixed  saliva  (spittle)  as  it  appears  in  the  mouth 
is  a  glairy,  frothy,  cloudy  fluid,  the  glairiness  or  ropiness  being 
due  to  mucus ;  micro-organisms  are  also  present  in  it  to  some 
extent,  and  other  foreign  matters  derived  from  the  food. 

Saliva  is  mainly  water  containing  but  little  solid  matter,  its 
specific  gravity  varying  from  1002  to  1006.  It  depends  for  its 
special  action,  as  a  digestive  solvent,  upon  a  ferment  it  contains 
called  ptyalin.1 

The  action  of  saliva  upon  the  food.  —  The  chief  function  of 
saliva  is  to  soften  and  moisten  the  food  and  to  assist  in  mastica- 
tion and  deglutition.  It  has,  however,  a  certain  solvent  action 
upon  food-stuffs,  especially  starch.  Upon  the  fats  and  proteids 
it  has  very  little  effect  except  to  render  them  softer  and  better 
prepared  for  the  action  of  the  other  digestive  juices. 

By  the  ptyalin-ferment  present  in  saliva,  starch,  which  is  an 
insoluble  substance,  is  changed  into  grape  sugar,  a  highly  solu- 
ble and  absorbable  product.  This  change  is  best  effected  at  the 
temperature  of  the  body,  in  a  slightly  alkaline  solution,  saliva 
that  is  distinctly  acid  hindering  or  arresting  the  process.  Boiled 
starch  is  changed  more  rapidly  and  completely  than  raw,  but 
the  food  is  never  retained  in  the  mouth  long  enough  for  the 
saliva  to  more  than  begin  the  transformation  of  starchy  matters. 
After  leaving  the  mouth,  further  conversion  of  starch  into  sugar 
is  arrested  by  the  acid  reaction  of  the  gastric  juice,  and  diges- 
tion of  this  class  of  food-stuffs  is  practically  suspended  until 
they  again  come  in  contact  with  the  alkaline  secretions  in  the 
upper  part  of  the  small  intestine. 

1  Ferments  are  either  organized  or  unorganized  bodies  ;  of  the  former  yeast 
is  a  well-known  example.  The  fermentative  power  of  yeast  which  leads  to  the 
conversion  of  sugar  into  alcohol  is  dependent  upon  the  life  of  the  yeast-cell. 
When  the  yeast-cell  dies,  fermentation  ceases.  Ptyalin  belongs  to  the  latter 
class ;  it  is  an  inorganic  substance,  not  a  living  organism  like  yeast. 


CHAP.  XV.]  ALIMENTATION.  171 

During  the  processes  of  mastication,  insalivation,  and  deglu- 
tition, the  food  is  first  reduced  to  a  soft  pulpy  condition ; 
secondly,  any  starch  it  may  contain  begins  to  be  changed  into 
sugar ;  thirdly,  it  acquires  a  more  or  less  alkaline  reaction.1 

Changes  the  food  undergoes  in  the  stomach.  —  The  entrance  of 
food  into  the  stomach  acts  as  a  stimulant  to  the  whole  organ. 
The  blood-vessels  dilate,  the  glands  pour  out  an  abundant  secre- 
tion upon  the  mucous  lining,  and  the  different  layers  of  the 
muscular  coat  are  excited  to  a  continuous  action.  Delayed  in 
the  stomach  by  the  contraction  of  the  pyloric  ring-muscle,  the 
pulpy  mass  of  food  is  carried  round  and  round,  and  thoroughly 
mixed  with  the  gastric  juice  until  it  is  dissolved  into  a  thick, 
grajdsh  soup-like  liquid,  called  chyme.  The  chyme  thus  formed 
is  from  time  to  time  ejected  through  the  pylorus,  accompanied 
by  morsels  of  solid,  less  well-digested  matter.  This  ejection 
may  occur  within  a  few  minutes  after  the  entrance  of  food  into 
the  stomach,  but  does  not  usually  begin  until  from  one  to  two 
hours  after,  and  lasts  from  four  to  five,  at  the  end  of  which 
time  the  stomach  is,  after  an  ordinary  meal,  completely  emptied. 

Gastric  juice.  —  Gastric  juice,  secreted  by  the  small,  tubular 
glands  in  the  mucous  lining  of  the  stomach,  is  a  thin,  colourless, 
or  pale  yellow  fluid,  of  an  acid  reaction.  It  contains  few  solids, 
and  is  dependent  for  its  specific  action  upon  a  ferment  called 
pepsin,  which  is  only  properly  active  in  an  acid  solution ;  and 
we  therefore  find  that  free  hydrochloric  acid  in  the  proportion 
of  0.2  per  cent  is  always  present  in  normal  gastric  juice. 

Action  of  gastric  juice  upon  the  food.  —  The  gastric  juice  has 
no  action  upon  starch,  and  upon  fats  it  has  at  most  a  limited 
action  ;  that  is,  if  adipose  tissue  be  eaten,  it  will  dissolve  the 
envelopes  of  the  fat-cell  and  set  the  fat  free,  but  it  has  no 
power  to  emulsify  them.  The  essential  property  of  gastric 
juice  is  the  power  it  has  of  dissolving  proteid  matters  and  of 
converting  them  into  a  substance  called  peptone.  Whatever 
the  proteid  may  be,  whether  the  albumin  of  eggs,  the  gluten  of 
flour  in  bread,  the  myosin  in  flesh,  the  result  is  the  same,  pepsin, 
in  conjunction  with  an  acid  at  the  temperature  of  the  body, 
transforms  them  into  peptones. 

Peptones  readily  dissolve  in  water,  and  pass  with  ease  through 
animal  membranes.  They  are  probably  absorbed,  as  soon  as 
1  Weak  alkalies  stimulate  the  gastric  glands  to  more  abundant  secretion. 


172  ANATOMY   FOR,  NUESES.  [CHAP.  XV. 

formed,  by  the  blood-vessels  in  the  walls  of  the  stomach, 
though  some  pass  in  the  chyme  through  the  pylorus  into  the 
small  intestine. 

Changes  the  food  undergoes  in  the  small  intestine.  —  The  chyme 
on  entering  the  duodenum,  after  an  ordinary  meal,  is  a  mixture 
of  various  matters.  It  contains  some  undigested  proteids  ;  some 
undigested  starch ;  oils  from  fats  eaten ;  peptones  formed  in  the 
stomach,  but  not  yet  absorbed ;  salines  and  sugar  which  have 
also  escaped  complete  absorption  in  the  stomach  ;  all  mixed  with 
a  good  deal  of  water  and  the  secretions  of  the  alimentary  canal. 
This  acid  mixture  passing  into  the  duodenum  excites  the  secre- 
tory action  of  the  pancreas,  and  stimulates  the  bile  to  flow  from 
the  gall-bladder;  the  glands  of  Lieberkiihn  and  Brunner  also 
become  active,  and  all  these  secretions  being  alkaline,  the  acid 
chyme  is  rapidly  changed  into  an  alkaline  preparation,  called 
chyle. 

Bile.  —  Bile,  secreted  in  the  lobules  of  the  liver  and  stored  in 
the  gall-bladder  until  needed,  is  a  fluid  of  a  bright  golden  red 
colour,  with  an  alkaline  reaction.  The  chief  solid  constituents 
of  bile  are  the  bile-salts  and  the  colouring-matters  or  pigments. 

Action  of  bile  on  food. —  Upon  proteids  and  starch,  bile  has 
little  or  no  digestive  action.  On  fats,  it  has  a  slight  solvent 
action,  and,  in  conjunction  with  pancreatic  juice,  has  the  power 
to  emulsify  them.  Bile  possesses  some  antiseptic  qualities. 
Outside  the  body,  its  presence  hinders  putrefactive  changes; 
and  when  it  is  prevented  from  flowing  into  the  alimentary 
canal,  the  contents  of  the  intestine  undergo  changes  which  do 
not  otherwise  take  place,  and  which  lead  to  the  appearance  of 
various  products,  especially  of  ill-smelling  gases.  Lastly,  the 
passage  of  fats  through  membranes  is  assisted  by  wetting  the 
membranes  with  bile  or  with  a  solution  of  bile-salts.  It  is 
known  that  oil  will  pass  to  a  certain  extent  through  a  filter- 
paper,  kept  wet  with  a  solution  of  bile-salts,  whereas  it  will 
not  pass,  or  passes  with  extreme  difficulty,  through  one  kept 
wet  with  distilled  water. 

Pancreatic  juice. — Healthy  pancreatic  juice  is  a  clear,  some- 
what viscid  fluid,  with  a  very  decided  alkaline  reaction.  It  is 
actively  secreted  by  the  pancreas  during  digestion  and  flows 
into  the  intestine  in  conjunction  with  the  bile.  The  Germans 
call  the  pancreas  the  "  abdominal  salivary  gland,"  though  the 


CHAP.  XV.]  ALIMENTATION.  173 

pancreatic  juice  has  a  far  more  extensive  action  than  the 
saliva. 

Among  other  important  constituents  the  pancreatic  juice  con- 
tains a  ferment  called  trypsin,  which,  like  pepsin,  has  the  power 
to  transform  proteids  into  peptones ;  trypsin,  however,  requires 
an  alkaline  medium  to  effect  this  transformation,  while  pepsin, 
as  we  have  already  seen,  requires  the  medium  to  be  acid. 

Action  of  pancreatic  juice  upon  food.  —  On  starch  pancreatic 
juice  acts  with  great  energy,  rapidly  converting  it  into  sugar. 
On  proteids  it  practically  exercises  the  same  influence  as  the 
gastric  juice,  for  by  it  proteids  are  changed  into  peptones.  On 
fats  it  has  a  twofold  action :  it  emulsifies  them,  and  it  splits 
them  up  into  fatty  acids  and  glycerine.  If  we  shake  up  olive 
oil  with  water,  the  two  cannot  be  got  to  mix:  as  soon  as  the 
shaking  ceases,  the  oil  floats  to  the  top;  but  if  we  shake  up 
olive  oil  with  pancreatic  juice,  the  oil  remains  evenly  suspended 
in  it.  The  reason  of  this  is,  that  the  oil  has  been  minutely 
divided  into  tiny  droplets,  and  each  droplet  surrounded  by  a 
delicate  envelope  supplied  from  the  albumin  in  the  pancreatic 
juice,  so  that  they  cannot  fuse  together  to  form  the  large  drops, 
which  would  soon  float  to  the  top.  The  pancreatic  juice,  in 
thus  emulsifying  the  fats,  gives  the  white  colour  to  the  chyle, 
which  is  its  most  striking  external  characteristic,  the  innumer- 
able tiny  oil-drops  reflecting  all  the  light  that  falls  on  its  sur- 
face. Secondly,  the  fats  that  are  not  emulsified,  are  broken  up 
into  glycerine  and  fatty  acids.  The  glycerine  is  absorbed,  and 
the  fatty  acids  in  the  presence  of  an  alkali  form  soaps  which  are 
soluble  in  water  and  capable  of  absorption. 

Thus  pancreatic  juice  is  remarkable  for  the  power  it  has  of 
acting  on  all  the  food-stuffs,  —  starch,  fats,  and  proteids. 

Succus  entericus,  or  intestinal  juice.  —  Succus  entericus  is  a 
clear,  yellowish  fluid,  having  a  faintly  alkaline  reaction  and 
containing  a  certain  quantity  of  mucus.  It  is  said  to  have  a 
solvent  action  upon  all  the  food-stuffs,  but  at  best  its  powers  are 
slow  and  feeble,  and  we  have  no  satisfactory  reasons  for  suppos- 
ing that  the  actual  digestion  of  food  in  the  intestine  is  to  any 
great  extent  aided  by  it. 

During  the  passage  of  the  food  through  the  small  intestine 
the  remaining  proteids,  starch,  and  fats  are  converted  into  pep- 
tones, sugar,  and  emulsified  fats  or  soluble  soaps,  and  these 


174  ANATOMY   FOR  NUKSES.  [CHAP.  XV. 

products  as  they  are  formed  pass  either  into  the  lymphatics, 
or  into  the  blood-vessels  in  the  intestinal  walls,  so  that  the 
contents  of  the  small  intestine,  by  the  time  they  reach  the  ileo- 
csecal  valve,  are  largely  deprived  of  their  nutritious  constitu- 
ents. So  far  as  water  is  concerned,  the  secretion  of  water  into 
the  small  intestine  maintains  such  a  relation  to  the  absorption 
from  it  that  the  intestinal  contents  at  the  end  of  the  ilium, 
though  otherwise  mucja  changed,  are  about  as  fluid  as  in  the 
duodenum. 

Changes  in  the  large  intestine.  —  We  have  no  very  definite 
knowledge  of  the  particular  changes  which  take  place  in  the 
large  intestine.  The  contents  become  distinctly  acid,  although 
the  secretions  of  the  intestinal  wall  are  alkaline,  and  certain 
acid  fermentations  must  therefore  take  place  in  them.  These 
are  probably  due  to  the  action  of  micro-organisms ;  but  however 
this  may  be,  the  chief  work  of  the  colon  is  absorption.  ' 

By  the  abstraction  of  all  the  soluble  constituents,  and  espe- 
cially by  the  withdrawal  of  water,  the  liquid  contents  become,  as 
they  approach  the  rectum,  changed  into  a  firm  and  solid  mass  of 
waste  matters,  ready  for  ejection  from  the  body,  and  called  feces. 

The  feces.  —  The  feces  consist  of  the  undigested  and  indigesti- 
ble substances  of  a  meal :  among  them  are  the  elastic  fibres  of 
connective  tissue ;  the  cellulose,  which  is  the  chief  constituent 
of  the  envelopes  encasing  the  cells  of  plants ;  the  indigestible 
mucin  of  mucus.  These  three  materials,  together  with  some 
water,  some  undigested  food-stuffs,  and  some  excretory  sub- 
stances found  in  the  various  secretions  poured  into  the  aliment- 
ary canal,  form  the  bulk  of  the  material  expelled  from  the  body. 

To  sum  up  the  digestive  processes  :  — 

The  transformation  of  the  food  we  take  into  our  mouths  into 
products  capable  of  absorption,  is  mainly  a  chemical  process. 
The  mechanical  subdivision,  bruising,  and  crushing  of  the  food, 
accomplished  by  the  teeth  and  the  muscular  contractions  of  the 
walls  of  the  alimentary  canal,  is  merely  a  process  of  preparation 
for  the  solvent  action  of  the  digestive  juices.  Of  these  juices 
there  are  five,  each  having  a  special  action. 

(1)  The    saliva,   containing   the    digestive   ferment   ptyalin, 
transforms  starch  into  sugar. 

(2)  The  gastric  juice,  containing  pepsin  (a  ferment  acting  in 
the  presence  of  an  acid),  transforms  proteids  into  peptones. 


CHAP.  XV.]  ALIMENTATION.  175 

(3)  The  pancreatic  juice,  containing  trypsin  (a  ferment  act- 
ing in  the  presence  of  an  alkali),  transforms  proteids  into  pep- 
tones, and,  by  virtue  of  other  constituents,  transforms  starch 
into  sugar,  and  emulsifies  fats  or  turns  them  into  soluble  soaps. 

(4)  Bile,  containing  bile-salts  and  other  matters,  assists  the 
pancreatic  juice  in  saponification  and  emulsion  of  fats,  promotes 
absorption  of  the  same,  and  modifies  putrefactive  changes  in  the 
intestine. 

(5)  Intestinal  juice,  containing  mucus,  transforms  all  food- 
stuffs  in  a  feeble  fashion,  not  clearly   demonstrated  nor  un- 
derstood. 

All  material  that  these  solvents  fail  to  transform  into  a  soluble 
and  absorbable  condition  is  gradually  worked  downwards  by  the 
peristaltic  contractions  of  the  alimentary  canal,  and  finally 
leaves  the  body  as  waste  and  useless  matter. 

NOTE.  —  For  the  sake  of  simplicity,  we  have  considered  digestion  in  a  broad 
way  as  the  conversion  of  practically  non-diffusible  proteids  and  starch  into  more 
diffusible  peptones  and  highly  diffusible  sugar,  and  as  the  emulsifying  of  fats. 
There  is  reason  to  believe  that  some  of  the  sugar  may  be  changed  into  lactic 
acid,  or  even  into  butyric  or  other  acids,  and  that  some  of  the  proteids  are  car- 
ried beyond  the  peptone  condition.  But  there  is  no  doubt  that  the  greater  part 
of  the  proteid  is  absorbed  as  peptone,  that  carbohydrates  are  mainly  absorbed 
as  sugar,  and  that  the  greater  part  of  the  fat  passes  into  the  body  as  an 
emulsion. 

Absorption.  —  We  have  now  to  consider  how  the  products  of 
digestion  find  their  way  out  of  the  alimentary  canal  into  the 
tissues  of  the  body;  for,  properly  speaking,  though  the  food  may 
be  digested  and  ready  for  nutritive  purposes,  it  is,  until  it 
passes  through  the  walls  of  the  alimentary  canal,  still  practi- 
cally outside  the  body. 

There  are  two  paths  by  means  of  which  the  products  of  diges- 
tion find  their  way  into  the  blood :  (1)  by  the  capillaries  in  the 
walls  of  the  stomach  and  intestines ;  and  (2)  by  the  lacteals  in 
the  walls  of  the  small  intestine. 

(1)  The  network  of  capillary  blood-vessels  is  spread,  as  we 
have  seen  (page  146),  immediately  beneath  the  basement  mem- 
brane of  the  mucous  coat  lining  the  interior  of  the  alimentary 
canal,  and  matters  in  solution  pass  readily  by  diffusion  or 
osmosis  from  the  interior  of  the  stomach  and  intestines  into 
the  blood-vessels  in  their  walls.  All  the  blood  from  the  diges- 


176  ANATOMY   FOE,   NUKSES.  [CHAP.  XV. 

tive  organs  is  taken  by  the  portal  vein  to  the  liver,  and  the 
products  of  digestion  are  modified  by  the  action  of  the  liver 
before  they  are  returned  to  the  general  circulation  by  the 
hepatic  veins.  The  hepatic  veins  pour  their  contents  into  the 
inferior  vena  cava,  and  the  blood,  enriched  with  the  products  of 
digestion,  finally  finds  its  way  into  the  right  side  of  the  heart, 
whence  it  is  taken  to  the  lungs  for  purification  before  being 
sent  to  all  parts  of  the  body. 

During  the  passage  of  the  blood  through  the  liver,  the  liver- 
cells  not  only  take  from  it  the  material  they  need  to  form 
the  bile ;  they  also  take  from  it  material  to  form  a  starchy  sub- 
stance, called  glycogen.  This  glycogen,  stored  in  the  liver-cells, 
is  gradually  doled  out,  as  it  is  needed,  to  the  blood.  It  is  not 
doled  out,  however,  in  the  form  of  glycogen,  which  closely 
resembles  starch,  and  is,  therefore,  insoluble,  but  in  the  form 
of  sugar  or  glucose.  Thus  the  liver  is  a  very  complex  organ 
whose  cells  elaborate  bile  and  glycogen,  and  by  some  fer- 
ment-body, contained  within  themselves,  convert  the  glycogen 
into  glucose. 

(2)  Matters  in  solution  can  pass  into  the  blood-vessels,  but 
some  other  provision  is  necessary  for  the  absorption  of  the 
emulsified  fats.  We  find,  accordingly,  in  the  villi,  which  so 
closely  cover  the  internal  surface  of  the  small  intestine,  little 
rootlets  or  beginnings  of  lymphatic  vessels,  which  are  set  apart 
for  the  absorption  of  the  fatty  products  of  digestion. 

These  lymphatic  rootlets  or  lacteals,  as  they  are  generally 
called,  occupy  the  centre  of  each  villus.  The  emulsified  fats 
pass,  probably  aided  by  the  bile,  into  the  bodies  of  the  columnar 
cells  on  the  surface  of  the  villi,  and  from  thence  find  their  way 
into  the  interior  of  the  villus,  and  finally  into  the  beginning  of 
the  lacteal.1  The  lacteals  carry  this  fatty  matter  or  chyle  to 
the  larger  lymphatics  in  the  mesentery,  and  these  empty  their 
contents  into  the  thoracic  duct  which  opens  into  the  great  veins 
on  the  right  side  of  the  neck. 

1  It  is  supposed  that  the  fat  gets  into  the  interior  of  the  lacteals  mainly  by 
the  action  of  the  leucocytes  or  lymph  corpuscles.  First,  the  fat  is  taken  up  by 
the  epithelium  cells  on  the  surface  of  the  villus,  and,  after  passing  through  them, 
is  taken  up  by  the  leucocytes  ;  next,  the  leucocytes  migrate,  carrying  the  fat 
particles  by  their  amoeboid  movements  into  the  lacteal ;  and  finally,  after  enter- 
ing the  lacteal,  they  dissolve  or  break  up  and  set  the  fat  particles  free. 


CHAP.  XV.]  ALIMENTATION.  177 

Thus  the  food  in  solution  finds  its  way  into  the  right  side  of 
the  heart  after  passing  through  the  liver,  and  the  emulsified 
food  after  passing  through  the  lymphatics.  It  is  not  to  be 
understood  that  matters  in  solution  do  not  find  their  way  into 
the  lacteals,  nor,  on  occasion,  emulsified  fats  into  the  blood- 
vessels, but,  broadly  speaking,  the  food-products  find  their  way 
into  the  blood  in  the  manner  above  described. 

Final  destination  of  food-stuffs.  —  It  is  impossible  to  say  defi- 
nitely what  becomes  of  the  different  food-principles  after  they 
have  once  entered  the  current  of  the  blood.  In  general,  it  may 
be  said  that  the  carbohydrates  are  used  for  the  production  of 
force,  and  that  the  fats  are  stored  in  the  body  and  used  as  fuel. 
The  proteids  do  all  that  can  be  done  by  the  fats  and  carbo- 
hydrates, and,  in  addition,  form  the  basis  of  blood,  muscles,  and 
all  the  connective  tissues. 

Still  we  cannot  say  that  the  carbohydrates  perform  a  certain 
work  in  the  body  and  nothing  else,  or  that  the  proteids  and  fats 
do.  It  is,  however,  generally  understood  that  the  proteids,  fats, 
and  carbohydrates  each  do  an  individual  work  of  their  own 
better  than  either  of  the  others  can  do  it.  They  are  also  neces- 
sary in  due  proportion  to  the  nutrition  of  the  body  and  work 
together  as  well  as  in  their  separate  functions. 

The  body  has  always  a  store  of  material  laid  by  for  future 
use.  If  this  were  not  the  case,  a  person  deprived  of  food  would 
die  immediately,  as  he  does  when  deprived  of  oxygen.  The 
great  reserve  forces  of  the  body  are  stored  in  the  form  of  adi- 
pose tissue  and  glycogen.  The  glycogen  is  given  out  during 
the  intervals  of  eating  to  supply  material  for  heat  and  energy ; 
the  adipose  tissue  is  not  so  readily  available,  but  may  be  called 
upon  during  prolonged  deprivation  from  food.  For  a  certain 
time  the  heat  of  the  body  may  be  maintained  and  work  done  on 
these  substances,  although  no  food  except  water  be  taken. 

In  conclusion  we  may  say  the  food  in  the  blood  supplies  the 
wants  of  the  body  in  five  different  ways :  — 

"1.   It  is  used  to  form  all  the  tissues  of  the  body. 

"  2.    It  is  used  to  repair  the  waste  of  all  the  tissues. 

"  3.   It  is  stored  in  the  body  for  future  use. 

"  4.  It  is  consumed  as  fuel  to  maintain  the  constant  tempera- 
ture which  the  body  must  always  possess  in  a  state  of  health. 

"  5.  It  produces  muscular  and  nervous  energy."  (Professor 
Atwater.)  N 


CHAPTER   XVI. 

ELIMINATION;    GENERAL    DESCRIPTION    OF    THE    URINARY    OR- 
GANS;  STRUCTURE  AND  BLOOD-SUPPLY  OF  KIDNEY;    SECRE- 
.      TION  OF  URINE;   COMPOSITION  AND   GENERAL   CHARACTERS 
OF  URINE. 

IN  the  last  four  chapters  we  have  seen  that  the  blood  is  con- 
stantly supplied  by  means  of  the  respiratory  and  digestive 
mechanisms,  with  all  the  chemical  substances  it  requires  to 
maintain  the  life,  growth,  and  activity  of  the  body.  These  sub- 
stances, entering  the  current  of  the  blood,  are  carried  to  all  the 
tissues,  and  are  incessantly  combining  with  the  chemical  sub- 
stances of  which  these  tissues  are  composed.  These  combina- 
tions are  not  left  to  chance ;  each  tissue  has  a  special  affinity 
for  the  chemical  substance  in  the  blood  which  it  requires  for  its 
own  growth  and  special  form  of  activity ;  the  secretory  cell  of 
the  liver  picks  out  substances  from  which  it  can  manufacture 
bile  and  glycogen ;  the  muscle  fibre  assimilates  those  that  will 
promote  the  changes  upon  which  depends  the  power  of  con- 
tractility. We  know  that  the  proteid  compounds  contain  the 
most  essential  elements  for  the  formation  of  all  kinds  of  tissue, 
and  that  phosphate  of  lime  is  a  necessary  ingredient  in  the 
hardening  of  bone,  but  we  are  utterly  ignorant  of  how  it  comes 
about  that  each  tissue  element  is  enabled  to  select  the  particular 
material  it  needs  and  to  reject  that  which  it  does  not  require. 

Our  bodies  are  masses  of  changing  atoms,  some  of  which,  if 
we  may  so  express  it,  are  on  the  "  up  grade,"  to  construct  the 
various  tissues,  and  some  are  on  the  "  down  grade,"  to  form  the 
waste  matters  which  are  the  final  products  of  the  tissues'  activ- 
ity. These  changes,  which  are  incessantly  going  on  while  life 
lasts,  are  described  under  the  general  term  of  metabolism  ;  the 
constructive  changes  being  spoken  of  as  anabolic,  and  the  de- 
structive as  katabolic,  changes.  The  final  products  then  of 

178 


CHAP.  XVI.]  ELIMINATION.  179 

the  metabolism  of  the  body  will  be  certain  waste  matters,  and 
we  shall  now  proceed  to  describe  the  mechanism  of  the  organs 
by  means  of  which  these  wastes  are  removed  from  the  body. 

Elimination.  —  In  passing  through  the  blood  and  tissues  of  the 
body,  the  proteids,  fats,  and  carbohydrates  are  transformed  into 
urea  (or  some  closely  allied  product),  carbonic  acid,  and  water, 
the  nitrogen  of  the  urea  being  furnished  by  the  proteids  alone. 
Many  of  the  proteids  contain  sulphur,  and  also  have  phosphorus 
attached  to  them  in  some  combination,  and  some  of  the  fats 
taken  as  food  contain  phosphorus ;  these  elements  are  converted 
by  oxidation  into  phosphates  and  sulphates,  and  are  excreted  in, 
that  form  in  company  with  the  other  salts  of  the  body. 

Broadly  speaking,  then,  the  waste  products  are  urea,  carbonic 
acid,  salts,  and  water.  These  leave  the  body  by  one  or  other  of 
three  main  channels,  the  lungs,  the  skin,  and  the  kidneys. 
Some  part,  it  is  true,  leaves  the  body  by  the  bowels,  for,  as  we 
have  seen,  the  feces  contain,  besides  undigested  portions  of  food, 
substances  which  have  been  secreted  into  the  bowels,  and  are 
therefore  waste  products  ;  but  the  amount  of  these  is  very  small 
and,  except  in  diseased  conditions,  of  no  special  importance. 

The  waste  matters  discharged  relatively  by  the  lungs,  skin, 
and  kidneys  may  be  stated  as  follows :  — 

By  the  lungs :        The  greater  part  of  the  carbonic  acid. 

A  considerable  quantity  of  water. 

By  the  skin :  A  variable  but,  on  the  whole,  large  quantity  of 

water. 

A  little  carbonic  acid. 

A  small  quantity  of  salts. 
By  the  kidneys :    All,  or  nearly  all,  the  urea  and  allied  bodies. 

The  greater  portion  of  the  salts. 

A  large  amount  of  water. 

A  very  small  quantity  of  carbonic  acid. 

We  have  already  studied  the  mechanism  by  means  of  which 
the  lungs  rid  the  blood  of  carbonic  acid  and  water,  and  it  now 
remains  for  us  to  consider  the  mechanism  of  the  skin  and  kid- 
neys. In  the  present  chapter  we  shall  devote  ourselves  to  the 
consideration  of  the  kidneys,  which  secrete  the  urine,  and  the 
other  urinary  organs,  the  ureters,  bladder,  and  urethra,  which 
collect  the  urine  arid  conduct  it  to  the  outside  of  the  body. 


180 


ANATOMY   FOB,   NURSES.          [CHAP.  XVI. 


Position  and  General  Description  of  the  Urinary  Organs. 

The  kidneys. The  kidneys  are  two  compound  tubular  secret- 
ing glands  placed  at  the  back  of  the  abdominal  cavity,  one  on 
each  side  of  the  lumbar  vertebrae.  They  are  bean-shaped,  with 
the  concave  side  turned  towards  the  spine,  and  the  convex  side 
directed  outwards.  Each  kidney  is  about  four  inches  long,  two 
broad,  and  one  thick,  and  extends  from  the  eleventh  rib  to  nearly 

the  crest  of  the  ilium,  the 
right  being  a  little  lower 
than  the  left  in  conse- 
quence of  the  large  space 
occupied  by  the  liver. 
They  are  covered  by  a 
tough  envelope  of  fibrous 
tissue  called  the  capsule 
of  the  kidney,  and  are 
usually  embedded  in  a  con- 
siderable quantity  of  fat. 

The  ureters.  —  The  ure- 
ters are  the  excretory  ducts 
of  the  kidneys.  They  arise 
in  the  middle  of  the  con- 
cave side,  or  hilus,  of  each 
kidney  and  proceed  ob- 
liquely downwards  and  in- 
wards through  the  lumbar 
region  of  the  abdomen  into 
the  pelvis,  to  open  ob- 
FIG.  105.  — THE  RENAL  ORGANS  VIEWED  ijmipiv  KV  two  constricted 
FROM  BEHIND.  R,  right  kidney;  At  aorta; 

Ar,  right  renal  artery ;  Vc,  inferior  vena  cava ;  orifices  into  the  base  of  the 
Vr,  right  renal  vein ;  U,  right  ureter ;  Vu,  -,  i  i  -,  TT>  -u  „  ; ,  ~f 

bladder;  Ua,  urethra.  bladder.    Each  ureter  is  ot 

the    diameter   of   a    goose. 

quill,  from  sixteen  to  eighteen  inches  long,  and  consists  of 
muscular  tissue  lined  by  mucous  membrane.  The  muscular  coat 
is  arranged  in  two  layers,  an  outer  circular  and  an  inner  longi- 
tudinal. Outside  the  muscular  coat  is  a  layer  of  fibrous  con- 
nective tissue  carrying  the  blood-vessels  and  nerves  with  which 
the  tube  is  supplied. 

The  bladder.  —  The  bladder  is  the  reservoir  of  the  urine.     It 


CHAP.  XVI:]  ELIMINATION.  181 

is  situated  in  the  pelvic  cavity  behind  the  pubes,  and  is  held  in 
position  by  ligaments.  During  infancy  it  is  conical  in  shape 
and  projects  above  the  upper  border  of  the  pubes  into  the  hypo- 
gastric  region.  In  the  adult,  when  quite  empty  it  is  placed 
deeply  in  the  pelvis ;  when  slightly  distended,  it  has  a  round 
form ;  but  when  greatly  distended,  it  is  ovoid  in  shape  and 
rises  to  a  considerable  height  in  the  abdominal  cavity. 
( Vide  Plate  VII.)  When  moderately  distended,  it  measures 
about  five  inches  in  length,  and  three  inches  across,  and  the 
ordinary  amount  of  urine  which  it  contains  is  about  one  pint. 
The  bladder  consists  of  plain  muscular  tissue  lined  by  a  strong 
mucous  membrane,  and  is  covered  partially  by  a  serous  coat 
derived  from  the  peritoneum.  The  muscular  coat  has  three 
layers,  the  principal  fibres  of  which  run  longitudinally  and  cir- 
cularly, the  circular  fibres  being  collected  into  a  layer  of  some 
thickness  around  the  constricted  portion  or  neck,  where  the 
bladder  becomes  continuous  with  the  urethra.  These  circular 
fibres  around  the  neck  form  a  sphincter  muscle  which  is  nor- 
mally in  a  state  of  contraction,  only  relaxing  at  intervals, 
when  the  accumulation  of  urine  within  the  bladder  renders  its 
expulsion  necessary. 

The  base  of  the  bladder  is  directed  downwards  and  back- 
wards, and  in  the  female  lies  in  contact  with  the  front  wall  of 
the  vagina  and  the  lower  part  of  the  neck  of  the  uterus.  The 
neck  of  the  bladder  is  directed  obliquely  downwards  and  for- 
wards. 

The  urethra.  —  The  urethra  is  a  narrow,  membranous  canal, 
about  an  inch  and  a  half  in  length  in  the  female,  and  extending 
from  the  neck  of  the  bladder  to  the  external  orifice  or  meatus 
urinarius.  It  is  placed  beneath  the  symphysis  pubis,  and  is 
embedded  in  the  anterior  wall  of  the  vagina.  Its  direction 
is  obliquely  downwards  and  forwards,  its  course  being  slightly 
curved,  the  concavity  directed  forwards  and  upwards.  It  ad- 
mits of  considerable  dilatation,  its  normal  diameter,  however, 
being  about  a  quarter  of  an  inch.  It  is  lined  by  a  mucous  coat, 
which  is  continuous,  externally,  with  that  of  the  vulva,  and, 
internally,  with  that  of  the  bladder.  The  external  muscular 
coat  is  also  continuous  with  that  of  the  bladder,  but  between 
the  mucous  and  muscular  coats  is  a  layer  of  thin,  spongy  tissue, 
containing  a  network  of  large  veins. 


182 


ANATOMY   FOB,   NUKSES.          [CHAP.  XVI. 


The  structure  of  the  kidney.  —  The  kidney  is  a  secreting  gland, 
constructed  upon  the  general  plan  of  a  compound  secreting 
gland,  but  possessing  special  features  peculiar  to  itself.  If  we 
cut  a  kidney  in  two  lengthwise,  it  is  seen  that  the  upper  end  of 
the  ureter  expands  into  a  basin-like  cavity,  into  which  the  solid 
portion  of  the  kidney  projects  in  conical-shaped  masses.  This 
dilated  cavity  of  the  ureter  is  called  the  pelvis  or  basin  of  the 
kidney,  and  this  pelvis  is  irregularly  subdivided  into  smaller, 

cup-like  cavities,  called  calices, 
which  receive  the  pointed  pro- 
jections of  the  kidney  substance. 
The  substance  of  the  kidney 
is  readily  seen  by  the  naked  eye 
to  consist  of  two  distinct  parts : 
an  outer,  darker,  and  more 
solid  portion,  called  the  cortex 
(bark),  and  an  inner,  lighter 
striated  portion,  called  the  me- 
dulla (marrow),  which  is  not  a 
solid  mass,  but  more  or  less 
distinctly  divided  into  pyra- 
midal -  shaped  sections.  The 
pointed  projections  or  papillw 
FIG.  106. -SECTION  THROUGH  THE  Qf  the  pyramids  are  received 
KIDNEY,  SHOWING  THE  MEDULLARY  AND  L  J 

CORTICAL   PORTIONS,  AND  THE   BEGIN-    by  the  irregularly  disposed  CUp- 

NING  OF  THE  URETER.    (Henie.)    Ct,   like  cavities  of  the  pelvis.    The 

cortex ;  M,  medulla ;  Py,  papilla  of  pyra- 
midal section,  projecting  into  one  of  the    bulk   of   the    kidney   Substance, 

artery-  °U  ureter.  *'  ^^   **'  ^    b°th  ln  the  COI>teX  and  medulla' 

is  composed  of   little  tubes  or 

tubules,  closely  packed  together,  having  only  just  so  much 
connective  tissue  as  is  sufficient  to  carry  a  large  supply  of 
blood-vessels  and  a  certain  number  of  lymphatics  and  nerves. 
The  different  appearance  of  cortex  and  medulla  is  due  to  shape 
and  arrangement  of  tubules  and  blood-vessels. 

Examined  under  the  microscope,  it  is  seen  that  the  urinifer- 
ous  tubules  begin  as  little  rounded  dilatations,  called  capsules, 
in  the  cortex  of  the  kidney.  These  capsules  are  joined  to  the 
tubules  by  a  constricted  neck,  and  the  tubules,  after  running  a 
very  irregular  course,  open  into  straight  collecting  tubes,  which 
pour  their  contents  through  openings  in  the  pointed  ends  or 


CHAP.  XVI.] 


ELIMINATION. 


183 


papilla  of  the  pyramids  into  the  pelvis  of  the  kidney.     (Vide 
Fig.  109.) 

The  tubules  are  composed  of  basement  membrane,  lined 
throughout  by  epithelium 
cells.  The  cells  vary  in 
the  different  parts  of  a 
tubule,  some  being  more 
especially  adapted  to  secre- 
tory purposes  than  others. 

The  blood-supply  of  the 
kidney.  —  For  its  size,  the 
kidney  is  abundantly  sup- 
plied with  blood.  The 
renal  artery,  coming  di- 
rectly from  the  aorta, 
divides  as  it  enters  the 
hilus  of  the  kidney  into 
branches,  which,  slipping 
around  the  pelvis,  pass 
inwards  between  the  pyra- 
mids. On  reaching  the 
boundary  line  between  the 
cortex  and  the  medulla, 
the  branches  divide  lat- 
erally to  form  more  or 
less  complete  arches,  (the 
veins  also  divide  in  a 
similar  manner  to  form 
venous  arches).  From  the 
arterial  arches,  vessels  pass 
upwards  through  the  cor- 
tex, giving  off  at  intervals  . 

p  .          (Cadiat.)     a,  part  of  arterial  arch;  b,  arterial 

tiny  arteries,  each  of  which    branch  passing  upwards  through  the  cortex; 

^  th        (lilnrpfl      pom-    c,  gloraerul us;  <Z,  efferent  vessel;  f,  raeshwork 

of    capillaries;  /,  straight   arterial  vessels  of 
meilCement    or    capsule    of    medulla;  g,  venous  arch;  h,  straight  veins  of 

a        uriniferous        tubule.  medulla- 

These  tiny  arteries,  entering  the  capsule,  are  spoken  of  as 
afferent  vessels.  They  push  the  thin  walls  of  the  capsule 
before  them,  break  up  into  a  knot  of  capillary  vessels,  called  a 
glomerulus,  and  finally  issue  from  the  capsule  as  efferent  ves- 


FIG.  107.  —  VASCULAR  SUPPLY  OF  KIDNEY. 


184  ANATOMY   FOR   NUESES.          [CHAP.  XVI. 

sels.  These  efferent  vessels  do  not  immediately  join  to  form 
veins,  but  break  up  into  a  close  meshwork  of  capillaries  around 
the  tubules,  before  they  unite  to  form  the  larger  vessels  and 
pour  their  contents  into  the  veins  forming  the  venous  arches, 
between  the  cortex  and  medulla.  In  this  way  the  cortex  of 
the  kidney  is  supplied  with  blood.  The  medulla  also  receives 
its  blood-supply  mainly  from  the  arterial  arches.  The  blood 
passes  downwards  in  straight  vessels  between  the  uriniferous 
tubules,  to  be  returned  by  more  or  less  straight  veins  to  the 
venous  arches,  whence  it  is  conveyed  by  large  branches  into 
the  renal  vein,  which  leaves  the  kidney  at  the  hilus  and  pours 
its  contents  into  the  inferior  vena  cava. 

The  renal  artery  in  passing  into  the  kidney  is  accompanied 
by  a  network  of  nerves,  called  the  renal 
plexus.  They  are  chiefly  vaso-motor  nerves, 
and  regulate  the  contraction  and  relaxation 
of  the  renal  blood-vessels. 

Secretion  of  urine.  —  Urine  is  secreted 
from  the  blood  in  two  ways.  It  is  partly 
removed  by  a  process  of  transudation  or  fil- 
tration, and  partly  by  the  secretory  action 
of  the  cells  lining  the  uriniferous  tubules. 

(1)  Into  the  dilated  extremity  or  capsule 
of  each  tubule  a  small  artery  enters  and, 

pushing   the  wall  of    the    capsule   before 
FIG.  108.  —  PLAN  OF  THE    •.    i        ?  .    .          i          i       «•  i  j          -i 

BLOOD  VESSELS  CONNECT-   lt»  Dreaks  up  into  a  bunch  of  looped  capll- 

ED  WITH  THE  TUBULES.      lanes.    The  blood  in  the  loop  of  capillaries 
or  glomerulus  is  only  separated  from  the 

interior  of  the  tubule  by  the  thin  walls  of  the  capillaries  and 
the  inverted  wall  of  the  capsule,  which  closely  covers  the 
glomerulus.  The  artery  entering  the  capsule  is  larger  than 
the  issuing  vein,  and,  during  its  passage  through  the  glom- 
erulus, the  blood  is  subjected  to  considerable  pressure.  As  a 
result  of  this,  a  transudation  of  the  watery  constituents  of  the 
blood,  with  some  dissolved  salts,  takes  place  through  the  walls  of 
the  blood-vessels  and  of  the  capsule  into  the  tubule. 

(2)  After  leaving  the  capsule,  the  efferent  vein  breaks  up 
into  a  meshwork  of  capillaries,  which  closely  surrounds  the 
tubules,  so  that  the  blood  is  again  brought  into  close  communi- 
cation with  the  interior  of  the  tubules.  The  tubules  are  lined 


CHAP,  XVI.] 


ELIMINATION. 


185 


with  secreting  cells,  and  these  cells  appear  to  have  the  power  of 
selecting  from  the  blood  the  more  solid  waste  matters  (especially 
the  urea),  which  fail  to  filter  through  the  flat  cells  forming  the 
wall  of  the  capsule. 

Thus  the  elimination  of  urine  is  a  double  process,  being  par- 
tially accomplished   by    transuda- 
tion,  and  partially  by  the  selective 
action  of  the  secreting  cells  lining 
the  tubules. 

Excretion  of  urine.  —  The  uri- 
niferous  tubules  commence  in  a 
dilated  extremity,  the  capsule,  arid, 
after  a  very  devious  course,  termi- 
nate in  the  collecting  tubules, 
which  open  on  the  pointed  projec- 
tions or  papillae  of  the  pyramids. 
The  fluid  they  contain  passes  into 
the  pelvis  of  the  kidney,  whence  it 
is  carried  along  the  ureters  into 
the  bladder,  partly  by  pressure  and 
gravity,  and  partly  by  the  peri- 
staltic contractions  of  the  muscular 
walls  of  the  ureters.  In  the  blad- 
der the  urine  collects,  its  return 
into  the  ureters  being  prevented  by 
the  oblique  entrance  of  these  tubes 
into  the  walls  of  the  bladder. 

Micturition  is  normally  caused 
by  the  accumulation  of  urine 
within  the  bladder.  The  accu-  r  FlG"  «».- DIAGRAM  OF  THE 

COURSE  OF  TWO  URINIFEROUS  TUB- 

mulation    Stimulates    the   muscular    ULES.      M,    malpighian    capsule,  or 

walk    tn    onntrapt      thp    rpsktannp    dilated  extremity ;  (7,  convoluted  por- 

Ct>     1  J    tion  of  tube ;  H,  loop,  consisting  of  a 

of  the  Sphincter  at  the  neck  of  the    descending  and  ascending  limb;  D, 

bladder  is  overcome,  and  the  urine  c 

is  ejected  through  the  urethra.  Involuntary  micturition  may 
occur  as  a  result  of  spinal  injury,  involving  the  nerve  centres 
which  send  nerves  to  the  bladder.  It  may  be  due  to  a  want 
of  "  tone  "  in  the  muscular  walls,  or  it  may  result  from  some 
abnormal  irritation. 

General  characters  of  the  urine.  —  Normal  urine  may  be  de- 


180  ANATOMY   FOR   NURSES.          [CHAP.  XVI. 

scribed  as  a  transparent  watery  fluid,  of  a  pale  yellow  colour, 
acid  reaction,  specific  gravity  of  1020,  and  possessing  an  odour 
which  can  only  be  described  as  "  characteristic  "  or  "  urinous.': 
Each  one  of  these  characters  is  liable  to  some  variation  within 
the  limits  of  health  as  well  as  in  disease. 

The  transparency  of  urine  may  be  diminished  in  health  by  the 
presence  of  mucus,  derived  from  the  geni to-urinary  tract,  or  by 
the  deposit  of  salts.  In  disease  the  urine  may  become  clouded 
by  the  presence  of  pus. 

The  colour  of  urine  depends  mainly  upon  the  amount  of  water 
it  contains;  also  upon  a  diminution  or  increase  of  colouring 
matters.  In  the  copious  urine  of  hysteria  the  colour  is  very 
light,  while  in  the  diminished  flow  in  fevers  it  is  very  high. 
Abnormal  colouring  matters  are  derived  from  food  or  medicine, 
or  result  from  some  diseased  condition. 

The  reaction  of  urine  should  always  be  tested  from  a  collec- 
tion of  urine  passed  during  twenty-four  hours,  as  it  is  affected 
by  diet  and  exercise.  The  reaction  of  mixed  urine  is  normally 
acid. 

The  specific  gravity  depends  upon  the  amount  of  solid  waste 
matters  present  in  the  urine.  In  health,  it  may  vary  from  1015 
to  1025.  When  the  solids  are  dissolved  in  a  large  amount  of 
water,  the  specific  gravity  will  naturally  be  lower  than  when, 
from  a  deficiency  of  water,  the  urine  is  more  concentrated.  It 
is  notably  heightened  by  the  presence  of  sugar  in  the  disease 
called  Diabetes  Mellitus. 

The  composition  of  urine.  —  The  chief  constituents  of  normal 
urine  are  water,  urea,  uric  acid,  colouring  matters,  and  salts.  Of 
these  constituents,  urea  is  by  far  the  most  important,  for  it  is 
the  chief  solid  waste  product  of  the  body.  To  eliminate  urea  is 
the  special  work  of  the  kidneys,  and  if  for  any  reason  they  fail 
to  execute  their  work,  the  accumulation  of  urea  in  the  system 
leads  to  termination  of  life.  Urea  is  the  final  product  of  all 
proteid  substances,  and  consequently  a  diet  rich  in  proteids 
will  increase  the  amount  of  urea  in  the  system.  When  the  kid- 
neys are  disabled,  it  is  customary  for  physicians  to  lighten  their 
work  as  far  as  possible  by  regulating  the  diet. 

Of  the  salts,  chloride  of  sodium  occurs  in  the  largest  quan- 
tity ;  it  sometimes  disappears  temporarily  from  the  urine  when, 
in  certain  inflammatory  diseases,  it  is  needed  by  the  blood. 


CHAP.  XVI.]  ELIMINATION.  187 

The  chief  abnormal  constituents  that  are  liable  to  appear  in 
the  urine  are  albumin,  giving  rise  to  a  condition  called  albu- 
minuria,  and  sugar,  giving  rise  to  diabetes.  The  "  casts,"  which 
are  found  in  urine  in  the  various  forms  of  Blight's  disease,  are 
shed  from  the  tubules  in  the  shape  of  cylindrical  moulds. 

The  quantity  of  urine  passed  in  twenty-four  hours.  —  The  normal 
quantity  of  urine  passed  in  twenty-four  hours  is  from  forty  to 
fifty  ounces,  or  about  three  pints.  This  will  vary  in  health 
with  the  condition  of  the  skin,  and  the  amount  of  fluid  taken 
into  the  body.  The  excretion  of  water  by  the  kidneys  is  closely 
related  to  that  excreted  by  the  skin.  When  the  body  is  exposed 
to  cold,  the  blood-vessels  in  the  skin  are  constricted,  and  the  dis- 
charge of  water  in  the  form  of  sweat  is  checked ;  at  the  same 
time  the  blood-vessels  of  the  kidneys  are  dilated,  there  is  a  full 
and  rapid  stream  of  blood  through  the  glomeruli,  and  an  in- 
creased flow  of  urine  results.  On  the  other  hand,  when  the 
body  is  exposed  to  warmth,  the  cutaneous  vessels  are  widely 
dilated,  and  the  skin  perspires  freely,  while  the  renal  vessels  being 
constricted,  only  a  small  and  slow  stream  of  blood  trickles 
through  the  glomeruli,  and  the  urine  which  is  secreted  is 
scanty.  The  effect  on  secretion,  however,  is  more  marked  by 
the  amount  of  fluid  absorbed  through  the  alimentary  canal ;  an 
increased  secretion  of  water  always  follows  an  ordinary  meal, 
and  when  large  quantities  of  water  are  drunk  the  amount  of 
urine  is  correspondingly  increased. 

The  supra-renal  capsules.  —  Lying  immediately  above  each  kid- 
ney are  two  small  flattened  bodies  of  a  yellowish  colour.  They 
are  usually  classified  with  the  ductless  glands,  as  they  have  no 
excretory  duct.  Each  organ  is  invested  by  a  fibrous  capsule 
which  sends  fibres  into  the  glandular  substance;  these  fibres 
form  a  framework  for  the  soft,  pulpy  substance  of  the  gland, 
and  within  the  spaces  of  the  framework  are  groups  of  cells. 

The  supra-renal  capsules  are  plentifully  supplied  with  blood- 
vessels, nerves,  and  lymphatics,  and  they  contain  some  striking 
colouring  matters.  In  disease  of  these  organs,  the  skin  fre- 
quently becomes  "  bronzed,"  from  an  increase  of  pigment  or 
colouring  matter.  Their  special  normal  functions  are  unknown. 


188 


ANATOMY  FOR  NURSES.  [CHAP.  XVI. 


AMOUNT  OF  THE  SEVERAL  URINARY  CONSTITUENTS 
PASSED  IN  TWENTY-FOUR  HOURS,  EXPRESSED  IN 
GRAMMES  AND  GRAINS.  (MARTIN.) 


Urine  in  24  hours. 

1500  grammes. 

23,250  grains. 

In  1000  parts. 

Water  

1428.00 

22,134.00 

959  00 

Solids   

72.00 

1  116  00 

4800 

The  solids  consist  of  — 
Urea      

33.00 

511  50 

2200 

050 

775 

0  33 

Hippuric  acid     

0.40 

620 

027 

100 

1550 

0  fifi 

Pigments  and  fats  

10.00 

15500 

6  66 

Sulphuric  acid    

200 

31  00 

1  33 

Phosphoric  acid      

300 

4fi  50 

9  OO 

7  00 

108  50 

A  7  A 

Ammonia  

075 

10  no 

0  50 

Potassium  ' 

2  50 

qQ  7« 

170 

Sodium      

noo 

170  50 

7  33 

Calcium     .... 

A  OK 

q  Q  A 

(\  -I  a 

Magnesium    

0  20 

q  00 

013 

71.60 

1110.00 

47.77 

CHAPTER  XVII. 


ELIMINATION  CONCLUDED:  THE  SKIN.  NAILS  AND  HAIR. 
BODILY  HEAT:  PRODUCTION  OF  HEAT;  LOSS  OF  HEAT. 
DISTRIBUTION  OF  HEAT;  REGULATION  OF  HEAT. 

HAVING  described  the  mechanism  by  means  of  which  the 
lungs  rid  the  body  of  carbonic  acid  and  water,  and  of  how  the  kid- 
neys relieve  it  of  urea,  salts,  and  water,  it  now  remains  for  us  to 
explain  how  the  skin  plays  its  part  in  elimination  by  yielding 
up  water,  and  a  certain  amount  of  carbonic  acid  and  salts. 

The  skin.  —  The  skin  is  not,  like  the  kidneys,  set  apart  to  per- 


-  sw 


M 


FIG.  110.  —  SECTION  OF  EPIDERMIS.  (Ranvier).  H,  horny  layer,  consisting  of 
s,  superficial  horny  scales;  sic,  swollen-out  horny  cells;  s.l.  clear  layer;  M,  Malpig- 
hian  layer,  consisting  of  s.gr.  granulur  layer;  p,  many-sided  or  prickle  cells;  c, 
columnar  cells.  Nerve  fihrils  may  be  traced  passing  up  between  the  epithelium  cells 
of  the  Malpighian  layer. 

189 


19o  ANATOMY  FOR   NURSES.         [CHAP.  XVII. 

form  one  special  function.  It  is  an  important  excretory  organ, 
but  it  Ls  also  an  absorbing  organ;  it  is  likewise  the  principal 
seat  of  the  sense  of  touch,  and  serves,  too,  as  a  protective  cover- 
ing for  the  deeper  tissues  lying  beneath  it. 

The  skin,  like  a  mucous  membrane,  consists  of  two  distinct 
layers;  an  epithelial  covering,  and  a  connective  tissue  basis. 
The  epithelium  is  a  stratified  epithelium  and  is  called  the  epi- 
dermis, or  scarf -skin;  the  connective  tissue  layer  is  called  the 
derma,  cutis  vera  (true  skin),  or  corium.  The  epidermis  is  com- 
posed of  layers  of  cells,  the  deeper  of  which  are  soft  and  pro- 
toplasmic, while  the  superficial  layers  are  hard  and  horny. 
Between  the  two  layers  is  a  fairly  distinct  line  of  granular- 
looking  cells,  the  granules  in  which  have  been  thought  to  form 
the  horny  matter  in  the  superficial  cells.  In  the  coloured  races 
the  single  layer  of  elongated  cells  next  the  corium  contains 
pigment  granules. 

The  growth  of  the  epidermis  takes  place  by  the  multiplication 
of  the  cells  in  the  deeper  or  Malpighian  layer.  As  these  cells 
multiply  by  cell-division,  they  push  upwards  towards  the  surface 
those  previously  formed.  In  their  upward  progress  they 
undergo  a  chemical  transformation,  and  the  soft  protoplasmic 
cells  become  converted  into  the  flat,  horny  scales  which  are 
constantly  being  rubbed  off  the  surface  of  the  skin. 

The  thickness  of  the  epidermis  varies  in  different  parts  of  the 
body,  measuring  in  some  places  not  more  than  21^0 th  of  an  inch, 
and  in  others  as  much  as  ^th  of  an  inch.  It  is  thickest  in  the 
palms  of  the  hands  and  soles  of  the  feet,  where  the  skin  is  most 
exposed  to  abrasion  and  pressure,  but  it  forms  a  protective  cover- 
ing over  every  part  of  the  true  skin,  upon  which  it  is  closely 
moulded. 

No  blood-vessels  pass  into  the  epidermis ;  it,  however,  receives 
fine  nerve-fibrils  between  the  cells  of  the  Malpighian  layer. 

The  cutis  vera  or  true  skin  is  a  highly  sensitive  and  vascular 
layer  of  connective  tissue.  It  is,  like  the  mucous  membranes, 
attached  to  the  parts  beneath  it  by  a  layer  of  areolar  tissue,  here 
named  "subcutaneous,"  which  layer,  with  very  few  excep- 
tions, contains  fat.  The  connection  in  some  parts  is  loose  and 
movable,  as  on  the  front  of  the  neck ;  in  others,  close  and 
firm,  as  on  the  palmar  surface  of  the  hand  and  the  sole  of  the 
foot. 


CHAP.  XVII.] 


THE   SKIN. 


191 


The  cutis  vera  is  often  described  as  consisting  of  two  layers, 
a  superficial  or  papillary  layer,  and  a  deeper  or  reticular  layer. 

The  surface  of  the  superficial  or  papillary  layer  is  increased 
by  protrusions  in  the  form  of  small  conical  elevations,  called 
papillae,  and  whence  this  layer  derives  its  name.  These  papillae 
contain  for  the  most  part  looped  blood-vessels,  but  they  also  con- 
tain the  terminations  of  medullated  nerve-fibres  in  the  shape  of 
little  bodies,  called  tactile  corpuscles. 

The  papillae  seem  chiefly  to  exist  for  the  purpose  of  giving 
the  skin  its  sense  of  touch,  being  always  well  developed  where 


FIG.  111.  —  SECTION  OF  SKIN  SHOWING  Two  PAPILLA:  AND  DEEPER  LAYERS  OF 
EPIDERMIS.  (Biesiadecki  )  a,  vascular  papilla,  with  capillary  loop  passing  from 
subjacent  vessel,  c;  h,  nerve-papilla,  containing  tactile  corpuscle,  t;  d,  nerve  passing 
up  to  tactile  body ;  /,/,  section  of  spirally  winding  nerve-tibres. 

the  sense  of  touch  is  exquisite.  The  papillae,  containing  tactile 
bodies,  are  specially  large  and  numerous  on  the  palm  of  the 
hand  and  the  tips  of  the  fingers,  and  on  the  corresponding 
parts  of  the  foot,  while  on  the  face  and  back  they  are  small  and 
irregularly  scattered. 

The  reticular  layer  of  the  corium  is  a  continuation  of  the 
papillary  layer,  there  being  no  real  division  between  them,  and 
is  made  up  of  bundles  of  white  fibrous  and  elastic  tissue  which 
gradually  blends  below  with  the  subcutaneous  areolar  tissue.  It 
contains  networks  of  blood-vessels,  lymphatics,  and  nerves. 


192  ANATOMY  FOR  NURSES.         [CHAP.  XVII. 

The  appendages  of  the  skin  are  the  nails,  the  hairs,  the 
sebaceous  glands,  and  the  sweat-glands.  They  are  all  devel- 
oped as  thickenings,  or  as  down-growths,  of  the  Malpighian 
layer  of  the  epidermis. 

The  nails.  —  The  nails  are  composed  of  clear,  horny  cells  of 
the  epidermis,  joined  together  so  as  to  form  a  solid,  continuous 
plate.  Underneath  each  nail,  the  true  skin  is  modified  to  form 
what  is  called  the  bed  or  matrix  of  the  nail.  This  bed  is  very 
vascular,  and  is  raised  up  into  numerous  papillse.  At  the 
hinder  part  of  the  bed  of  the  nail  the  skin  forms  a  deep  fold,  in 
which  is  lodged  the  root  of  the  nail. 

The  growth  of  the  nail  is  accomplished 
by  constant  multiplication  of  the  soft 
cells  in  the  Malpighian  layer  at  the  root. 
These  cells  are  transformed  into  dry,  hard 
scales,  which  unite  into  a  solid  plate,  and 
the  nail,  constantly  receiving  additions 
from  below,  slides  forward  over  its  bed  and 
projects  beyond  the  end  of  the  finger. 
When  a  nail  is  thrown  off  by  suppuration, 
or  torn  off  by  violence,  a  new  one  will  grow 
in  its  place,  provided  any  of  the  cells  of 
the  Malpighian  layer  are  left. 

The  average  rate  of  growth  of  the  nails 

FIG.    112.— PIECE   OF  is  about  7V  of  an  incn  Per  week. 
HUMAN     HAIR.      (Highly         _..       _     .  ,-,,        ,     .  ,,          » 

magnified.)  a,  cuticle;  The  hairs.  —  The  hairs  are  growths  of 
b,  fibrous  substance;  c,  the  epidermis,  developed  in  little  pits,  the 

medulla.  .         ...  .  ,  . 

hair-follicles,  which  extend  downwards  into 

the  deeper  part  of  the  true  skin,  or  even  into  the  subcu- 
taneous tissue.  The  hair  grows  from  the  bottom  of  the  little 
pit  or  follicle,  the  part  which  lies  within  the  follicle  being 
known  as  the  root.  The  substance  of  the  hair  is  composed 
of  coalesced  horny  cells,  arranged  in  different  layers,  and  we 
usually  distinguish  three  parts  in  the  stem  or  shaft  of  hairs. 
An  outer  layer  of  delicate,  scale-like  cells,  the  cuticle ;  a  middle, 
horny,  thick,  and  coloured  portion,  formed  of  elongated  cells, 
the  fibrous  substance;  and  a  central  pith  formed  of  angular  cells, 
the  medulla. 

The  root  of  the  hair  is  enlarged  at  the  bottom  of  the  follicle 
into  a  bulb  or  knob,  and  this  bulb  is  composed  of  soft-growing 


CHAP.  XVII.]  THE   HAIES.  193 

cells,  and  fits  over  a  vascular  papilla  which  projects  into  the 
bottom  of  the  follicle.  The  hair  grows  from  the  bottom  of 
the  follicle  by  multiplication  of  the  soft  cells  which  cover  the 
papilla,  these  cells  becoming  elongated  to  form  the  fibres  of  the 
fibrous  portion,  and  otherwise  modified  to  form  the  medulla  and 
cuticle.  New  hairs  are  produced  indefinitely,  so  long  as  the 
papillae  and  soft  cells  remain  intact. 

The  follicles  containing  the  hairs  are  narrow  pits  formed  by 
the  involutions  of  the  true  skin  and  the  epidermis.  They  slant 
obliquely  upwards,  so  that  the 
hairs  they  contain  lie  down  on 
the  surface  of  the  body.  Con- 
nected with  each  follicle  are 
small  muscles  of  plain  muscular 
tissue  which  pass  from  the  sur- 
face of  the  true  skin,  on  the  side 
to  which  the  hair  slopes,  obliquely 
downwards,  to  be  attached  to  FlG-  H3.  — SECTION  OF  THE  SKIN 

,    ,  -   ,    „  ,         _          SHOWING  THE  HAIRS  AND  SEBACEOUS 

the  bottom  Ot  the  lollicle.    When     GLANDS,    a,  the  epidermis;  6,  corium; 

these    muscles    Contract,  as   thev     C>  muscles»  attached  to  hair-follicles  and 

J      to  under  surface  of  epidermis. 

will  under  the  influence  of  cold 

or  terror,  the  little  hairs  are  pulled  up  straight,  and  stand  "  on 
end " ;  the  follicle  also  is  dragged  upwards  so  as  to  cause  a 
prominence  on  the  surface  of  the  skin,  whilst  the  cutis  vera, 
from  which  the  little  muscle  arises, is  correspondingly  depressed: 
in  this  way  the  roughened  condition  of  the  skin  known  as 
"  goose-skin "  is  produced.  Hairs  grow  on  an  average  at  the 
rate  of  half  an  inch  per  month.  They  are  found  all  over  the 
body,  except  on  the  palms  of  the  hands  and  the  soles  of  the 
feet,  and  on  the  last  joints  of  the  fingers  and  toes. 

The  sebaceous  glands.  —  The  sebaceous  glands  are  small  saccu- 
lar  glands,  the  ducts  of  which  open  into  the  hair-follicles.  They 
are  lined  with  epithelium,  and  secrete  a  fatty,  oily  substance 
(sebum)  which  they  discharge  into  the  hair-follicles.  Several 
sebaceous  glands  may  open  into  the  same  follicle,  and  their  size 
is  not  regulated  by  the  length  of  the  hair.  Thus,  some  of  the 
largest  are  found  on  the  nostrils  and  other  parts  of  the  face, 
where  they  often  become  enlarged  with  pent-up  secretion.  The 
sebum  lubricates  the  hairs  and  renders  them  glossy;  it  also 
exudes,  more  or  less,  over  the  whole  surface  of  the  skin,  and 


194 


ANATOMY   FOB,  NURSES.        [CHAP.  XVIL 


keeps  it  soft  and  flexible.  An  accumulation  of  this  sebaceous 
matter  upon  the  skin  of  the  foetus  furnishes  the  thick,  cheesy  r 
oily  substance,  called  the  vernix  caseosa. 

The  sudoriferous  or  sweat-glands,  —  All  over  the  surface  of  the 
skin  are  minute  openings  or  pores.  These  pores  are  the  open- 
ings through  which  the  sweat-glands  pour  their  secretions  upon 
the  surface  of  the  body.  The  sweat-glands  are  tubular  glands 
with  their  blind  ends  coiled  into  little  balls  which  are  lodged 
in  the  true  skin  or  subcutaneous  tissue  ;  from  the  ball  the  tube 
is  continued  as  the  excretory  duct  of  the  gland  up  through 
the  true  skin  and  epidermis,  and  finally  opens  on  the  surface 
by  a  slightly  widened  orifice.  Each  tube  is  lined  by  a  secreting 

epithelium  continuous 
with  the  epidermis.  The 
coiled  end  is  closely  in- 
vested by  a  mesh  work  of 
capillaries,  and  the  blood 
in  the  capillaries  is  only 
separated  from  the  cav- 
ity of  the  glandular  tube 
by  the  thin  membranes 
which  form  their  respec- 
tive walls.  The  secre- 
tory apparatus  in  the 
skin  is  somewhat  simi- 

FIG.  114.  — COILED  END  OF  A  SWEAT-GLAND,  lar  to  that  which  obtains 
a,  the  coiled  end ;  b,  the  duct ;  c,  network  of  capil-  in  the  kidnev  '  in  the 
laries,  inside  which  the  sweat-gland  lies.  J  ' 

one  case  the  blood- 
vessels are  coiled  up  within  the  tube,  while  in  the  other  the 
tube  is  coiled  up  within  the  meshwork  of  blood-vessels. 

The  sweat-glands  are  abundant  over  the  whole  skin,  but 
they  are  most  numerous  on  the  palm  of  the  hand  and  on  the  sole 
of  the  foot;  in  the  groin,  and  especially  in  the  axilla,  they  are 
larger  than  in  other  parts  of  the  body.  At  a  rough  estimate, 
the  whole  skin  probably  possesses  from  two  to  two  and  a  half 
millions  of  these  glands,  and  their  combined  secreting  power  is 
therefore  very  great. 

Perspiration  or  sweat.  —  The  sweat  is  a  transparent  colourless 
fluid,  of  a  distinctly  salt  taste  and  with  a  strong,  distinctive  odour. 
When  the  secretion  is  scanty  it  has  an  acid  reaction,  but  when 


CHAP.  XVIL]      ELIMINATION   CONCLUDED.  195 

abundant  it  is  alkaline.  The  chief  normal  constituents  of  sweat 
are  water,  salts,  fatty  acids,  and,  some  authorities  state,  a  slight 
amount  of  urea.  In  various  forms  of  kidney  disease  urea  may 
be  present  in  considerable  quantity,  the  skin  supplementing  to 
a  certain  extent  the  deficient  work  of  the  renal  organs. 

Quantity  of  perspiration.  —  Under  ordinary  circumstances,  the 
perspiration  that  we  are  continually  throwing  off  evaporates 
from  the  surface  of  the  body  without  our  becoming  sensible  of 
it.  This  insensible  perspiration,  as  it  is  called,  usually  amounts 
to  about  twenty  or  thirty  ounces  in  the  course  of  twenty-four 
hours.  The  amount,  however,  varies  to  a  great  extent  —  with 
the  condition  of  the  atmosphere ;  the  amount  of  exercise  taken ; 
the  quantity  of  fluid  drunk ;  the  action  of  the  kidneys.  Varia- 
tions also  occur  under  the  influence  of  mental  emotions,  the 
action  of  drugs,  or  are  induced  by  certain  diseased  conditions. 
When  more  sweat  is  poured  upon  the  surface  of  the  body  than 
can  be  removed  at  once  by  evaporation,  it  appears  on  the  skin 
in  the  form  of  scattered  drops,  and  we  then  speak  of  it  as  sen- 
sible perspiration. 

Less  important  functions  of  the  skin.  —  Besides  being  an  impor- 
tant excretory  organ,  the  skin  is  to  a  slight  extent  an  absorbing 
organ.  In  the  sound,  healthy  skin,  it  is  doubtful  whether 
matters  in  solution  can  be  absorbed  through  the  epidermic 
covering,  but  if  the  horny  layers  of  the  epidermis  be  removed 
by  blistering,  matters  in  solution  readily  pass  into  the  blood- 
vessels in  the  true  skin.  Oily  substances,  especially  when  well 
rubbed  in,  are  absorbed  without  removal  of  the  epidermis. 

Oxygen  in  small  amount  is  also  taken  in  through  the  skin, 
but  this  gain  to  the  body  is  counterbalanced  by  the  carbonic 
acid  which  is  thrown  off. 

To  sum  up :  the  skin  excretes  a  large  amount  of  water  and  a 
small  amount  of  carbonic  acid  and  salts;  it  absorbs  a  small 
amount  of  oxygen  and,  under  certain  conditions,  oily  substances 
and  watery  solutions ;  it  is  a  protective  organ  and  a  tactile 
organ ;  it  supports  two  appendages,  viz.,  the  hair  and  nails,  and 
keeps  itself  flexible,  and  the  hair  glossy,  by  the  secretion  of 
sebum. 

There  is  still  another  function  of  the  skin  to  be  considered 
before  closing  this  chapter,  and  that  is  the  part  it  plays  in  regu- 
lating the  temperature  of  the  body. 


196  ANATOMY   FOE   NUKSES.         [CHAP.  XVII. 

Bodily  heat.  —  In  order  that  the  bodily  functions  may  be  prop- 
erly performed,  it  is  necessary  for  the  body  to  maintain  a  certain 
temperature.  Just  as  plants  are  killed  by  the  frost,  or  withered 
by  the  heat  of  the  sun,  so  our  tissues  die  if  the  bodily  tempera- 
ture falls  below,  or  rises  above,  a  certain  limit.  Our  bodies, 
however,,  differ  from  plants  in  that  they  generate  and  regu- 
late their  own  temperature,  and  possess  the  power  of  adapting 
themselves  to  extremes  of  external  heat  and  cold,  without 
necessarily  suffering  any  vital  injury.  But,  although  the  ex- 
ternal temperature  of  the  atmosphere  may  vary  considerably 
without  hurting  us,  the  bodily  temperature  must  be  kept  at 
an  average  standard  of  98.6°  F.  (37°  C.)  if  we  are  to  remain  in 
a  state  of  health.  Slight  variations  are  compatible  with  health, 
the  temperature  being  normally  a  trifle  higher  after  eating  or  in 
the  evening  of  the  day,  but  any  variation  over  a  degree  above  or 
below  98.6°  F.  is  indicative  of  danger. 

Production  of  heat.  —  Heat  in  the  body  is  produced  by  the 
chemical  changes  that  are  constantly  going  on  in  the  tissues. 
Wherever  metabolic  changes  are  taking  place,  there  heat  is  set  free. 
These  changes  take  place  more  rapidly  in  some  tissues  than  in 
others,  and  in  the  same  tissues  at  different  times.  The  muscles 
always  manifest  a  far  higher  rate  of  activity  than  the  connec- 
tive tissues,  and  consequently  the  former  evolve  a  larger  pro- 
portion of  the  bodily  heat  than  the  latter.  We  might  liken  the 
different  tissues  of  the  body  to  so  many  fireplaces  stored  with 
fuel,  the  fuel  in  some  of  the  fireplaces  being  more  easily  ignited 
and  burning  more  rapidly  than  in  others.  The  muscles  and  the 
secreting  glands,  especially  the  liver,  are  supposed  to  be  the 
main  sources  of  heat,  as  they  are  the  seats  of  a  very  active 
metabolism. 

Loss  of  heat.  —  The  heat  thus  continually  produced  is  as  con- 
tinually leaving  the  body  by  the  skin  and  the  lungs,  and  by  the 
urine  and  feces.  It  has  been  calculated  that  in  every  100  parts 
about :  — 


88  per  cent  is  lost  by  conduction  and  radiation  from  the  surface  of 
the  skin  and  the  evaporation  of  the  perspiration. 

9  per  cent  is  lost  by  warming  the  expired  air  and  the  evaporation 
of  the  water  of  respiration. 

3  per  cent  is  lost  by  warming  the  urine  and  feces. 


CHAP.  XVII.]  BODILY   HEAT.  197 

Distribution  of  heat.  —  The  blood,  as  we  know,  permeates  all 
the  tissues  in  a  system  of  tubes  or  blood-vessels.  Wherever 
oxidation  takes  place  and  heat  is  generated,  the  temperature  of 
the  blood  circulating  in  these  tissues  is  raised.  Wherever,  on 
the  other  hand,  the  blood-vessels  are  exposed  to  evaporation, 
as  in  the  moist  membranes  in  the  lungs,  or  the  more  or  less 
moist  skin,  the  temperature  of  the  blood  is  lowered.  The  gain 
and  loss  of  heat  balance  one  another  with  great  nicety,  and 
the  blood,  circulating  rapidly,  now  through  warmer,  and  again 
through  cooler  tubes,  is  kept  at  a  uniform  temperature  of  about 
100°  F.  In  this  way  the  whole  body  is  warmed  in  somewhat 
the  same  way  as  we  warm  a  house,  the  warm  blood  in  the  blood- 
vessels heating  the  tissues,  as  the  hot  water  in  the  hot-water 
pipes  heats  the  rooms  in  steam-heated  dwellings. 

Regulation  of  heat.  —  We  have  seen  that  active  changes  in 
the  body  produce  heat.  The  action  of  the  muscles  is  a  source 
of  heat,  the  activity  of  the  glands  during  digestion,  the  active 
changes  taking  place  in  the  tissues  during  inflammation  or 
suppuration,  or  the  changes  caused  by  some  specific  micro- 
organism, and  we  may  say  that  there  are  normal  and  abnormal 
sources  of  heat. 

Normally,  production  of  heat  is  balanced  by  loss  of  heat,  and 
the  chief  regulator  of  this  gain  and  loss  is  undoubtedly  the 
skin.  This  is  well  seen  in  the  case  of  muscular  exercise. 
Every  muscular  contraction  gives  rise  to  heat,  and  yet  during 
severe  muscular  exercise  the  temperature  of  the  body  does  not 
rise,  or  rises  only  to  a  trifling  extent.  This  is  accounted  for 
by  the  fact  that  when  the  muscular  exertion  causes  the  blood 
to  circulate  more  quickly  than  usual,  the  blood-vessels  in  the 
skin  dilate,  the  sweat-glands  at  the  same  time  are  excited  to 
pour  out  a  more  abundant  secretion,  and  the  heated  blood  pass- 
ing in  larger  quantities  through  the  cutaneous  vessels  (which 
are  kept  well  cooled  by  the  evaporation  of  the  perspiration), 
the  general  average  temperature  of  the  body  is  maintained. 

In  pyrexia,  or  fever,  rise  of  temperature  is  due  to  some  cause 
which,  while  increasing  the  metabolism  of  the  tissues,  at  the 
same  time  interferes  with  the  process  by  means  of  which  the 
body  rids  itself  of  superfluous  heat.  We  all  know  how  hot  and 
dry  the  skin  is  liable  to  become  in  fevers ;  how  we  try  to  restore 
its  function  and  lower  the  temperature  by  baths,  sponging,  and 


198  ANATOMY   FOR    NUESES.         [CHAP.  XVII. 

packs ;  how  we  recognize  the  first  signs  of  restored  function  — 
the  moist,  warm  sweat  in  the  palm  of  the  hand  —  as  a  pretty 
sure  sign  that  the  fever  is  "  broken."  If  a  very  high  tempera- 
ture persists  for  any  length  of  time,  the  metabolism  of  the 
tissues  goes  on  at  such  a  rapid  rate  that  the  capital  of  the  body 
is  soon  exhausted.  Every  organ  works  with  feverish  activity, 
the  heart  and  lungs  increase  their  action,  the  pulse  and  respira- 
tion become  more  and  more  hurried,  and  consequently  more  and 
more  feeble,  until  finally,  unless  relief  is  obtained,  the  patient 
dies  of  exhaustion. 

In  exposure  to  variations  of  external  temperature,  the  skin  is 
also  the  chief  agent  in  regulating  the  heat  of  the  body.  Expos- 
ure to  cold  causes  the  blood-vessels  in  the  skin  to  contract,  the 
cold  acting  as  a  stimulus  to  the  vaso-motor  nerves,  which  con- 
trol the  calibre  of  the  cutaneous  blood-vessels.  As  a  result, 
less  blood  is  sent  to  the  surface  to  be  cooled,  and  the  average 
blood-temperature  is  maintained.  On  the  other  hand,  exposure 
to  warmth  causes  the  cutaneous  blood-vessels  to  dilate,  and 
more  blood  is  sent  to  the  surface  to  be  cooled.  Briefly,  when 
the  external  temperature  is  high,  the  cutaneous  blood-vessels 
dilate,  and  the  sweat  is  also  usually  poured  out  upon  the  sur- 
face of  the  skin  ;  when  the  external  temperature  is  low,  the  cuta- 
neous blood-vessels  contract,  and  the  skin  usually  remains  dry. 

By  clothing  we  can  aid  the  functions  of  the  skin  and  the 
maintenance  of  heat ;  though,  of  course,  clothes  are  not  in  them- 
selves sources  of  heat.  The  object  of  clothing  is,  in  winter,  to 
prevent  conduction,  radiation,  and  evaporation  of  heat  from  the 
skin,  and,  in  summer,  to  promote  it.  Of  the  materials  used  for 
clothes,  linen  is  a  good  conductor ;  calico  or  muslin  not  quite  so 
good,  while  wool,  silk,  and  fur  are  all  bad  conductors. 

Subnormal  temperature.  —  In  some  maladies  the  temperature 
falls  distinctly  below  the  normal.  This  is  no  doubt  chiefly  due 
to  diminished  metabolism.  In  cases  of  starvation,  the  fall  of 
temperature  is  very  marked,  especially  during  the  last  days  of 
life.  The  diminished  activity  of  the  tissues  first  affects  the 
central  nervous  system ;  the  patient  becomes  languid  and 
drowsy,  and  finally  unconscious ;  the  heart  beats  more  and 
more  feebly,  the  breath  comes  more  and  more  slowly,  and  the 
sleep  of  unconsciousness  passes  insensibly  into  the  sleep  of 
death. 


CHAPTER  XVIII. 

NERVOUS  TISSUE.— THE  CEREBRO-SPINAL  SYSTEM:  BRAIN  AND 
CRANIAL  NERVES;  SPINAL  CORD  AND  SPINAL  NERVES.— 
SYMPATHETIC  SYSTEM. 

Nervous  tissue. — Nervous  tissue  is  the  most  highly  organized 
tissue  of  the  body.  It  is  pre-eminently  the  "master  tissue," 
controlling,  regulating,  and  directing  all  the  other  tissues. 
Like  muscular  tissue,  it  is  irritable  and  responds  to  stimuli; 
but,  unlike  muscular  tissue,  it  is  not  contractile. 

If  we  stimulate  a  nerve-fibre,  certain  molecular  changes  are 
started  in  the  fibre,  and  these  changes  are  transmitted  along 
the  fibre  without  visibly  altering  its  form.  We  call  these 
changes  thus  propagated  along  a  fibre,  "nervous  impulses." 
The  stimuli  that  start  these  nervous  impulses  are  varied  and 
numerous,  and  may  originate  from  within  the  body  as  well  as 
from  without.  They  usually  originate  from  without;  as,  for 
example,  a  ray  of  light  falls  on  the  nervous  tissue  of  the  eye, 
the  light  stimulates  and  sets  up  changes  in  the  nervous  tis- 
sue which  are  transmitted  along  the  optic  nerve  to  the  brain. 
These  nervous  impulses  reaching  the  brain  may  start  other 
nervous  impulses,  which,  travelling  down  certain  nerves  to 
certain  muscles,  will  cause  those  muscles  to  contract,  in  which 
case  we  say  a  man  starts.  Again,  sound  falling  on  the  ear,  a 
drop  of  water  falling  on  the  hand,  some  change  in  the  air  or 
other  surroundings  of  the  body,  or  some  change  within  the  body 
itself,  may  so  affect  the  nervous  tissue  that  nervous  impulses 
are  started  and  travel  to  this  point  or  that,  giving  rise  to  move- 
ment as  they  reach  muscular  tissue,  or  producing  some  other 
effect  as  they  reach  other  tissues.  We  may  say  that  nervous 
tissue  generates,  transforms,  and  propagates  nervous  impulses. 

When  subjected  to  the  microscope,  nervous  tissue  is  seen  to 

199 


200 


ANATOMY   FOR   NURSES.      [CHAP.  XVI1L 


consist  of  two  different  structural  elements,  viz.,  fibres  and 
cells,  both  of  which  are  enclosed  and  supported  by  a  peculiarly 
arranged  connective  tissue,  and  supplied  with  blood  and  lym- 
phatic vessels.  These  fibres  and  cells  are  arranged  in  distinct 
masses,  called  "  nerve-centres,"  or  in  the  form  of  cords,  called 
u  nerves."  The  nervous  cords  are  composed  almost  entirely  of 
the  nerve-fibres,  while  the  nerve-centres  contain  both  fibres 

and  cells.  The  nerves  con- 
duct or  propagate  nervous 
impulses,  while  the  nerve- 
centres  generate,  transmit, 
and  store  them. 

Nerve-cells.  —  Nerve-cells 
vary  much  in  size  and 
shape ;  many  are  large, 
some  being  amongst  the 
largest  cells  met  with  in 
the  body  ;  others,  again,  are 
quite  small.  The  nucleus 
is  generally  large,  clear, 
and  spherical,  with  a  single 
large  and  distinct  nucleolus. 
The  cell  substance  is  finely 
granular,  sometimes  is  in- 
distinctly striated.  All 
nerve-cells  have  at  least  one 
process  or  branch,  —  most 
of  them  have  more;  and 
they  are  often  spoken  of,  in 
consequence,  as  uni-polar, 
bi-polar,  and  multi-polar 
cells.  In  many  nerve-cells 
we  recognize  two  distinct 
kinds  of  processes :  first, 
those  which,  soon  after 
leaving  the  cell,  divide  and  subdivide,  until  they  become  exceed- 
ingly fine  and  delicate,  and  in  some  cases  seem  to  join  equally 
processes  from  other  cells;  second,  those  which  do  not 


FIG.  115.  —  MULTI-POLAR  NERVE-CELL. 
(Gerlach.)  a,  axis-cylinder,  or  nerve-fibre 
process;  b,  pigment. 


fine 


divide  and  subdivide,  but  are  prolonged  as  nerve-fibres. 

Nerve-fibres.  —  These  are  of  two  kinds  :  those  having  a  sheath 


CHAP.  XVIII.]        THE  NERVOUS   TISSUE. 


201 


6       c      d     e    / 
FIG.   116. — NERVE-FIBRES. 


3 

a,  nerve- 


of  white  substance,  and  called  medullated  nerve-fibres ;  and  those 
having  no  white  sheath,  called  non-medullated  nerve-fibres. 

The  medullated  nerve-fibres  consist  of  three  parts:  (1)  the 
axis-cylinder;  (2)  the  white,  or  medullary  sheath;  (3)  the 
neurilemma,  or  enclosin-g  sheath. 

(1)  The  axis-cylinder  is  the  essential  part  of  every  nerve- 
fibre,  and  runs  as  a  somewhat  indistinct  strand  in  the  axis  of 
the  fibre,  and  it  is  sometimes 

called  the  axis-band.  It  ap- 
pears to  be  in  every  case  a 
direct  prolongation  of  a  branch 
of  a  nerve-cell,  and  may  there- 
fore be  looked  upon  as  a  far- 
extending  cell -process.  It 
passes  without  any  break  or 
interruption  from  the  nerve-  fibre>  showing  complete  interruption  of 

Centres  to  the    periphery;    that  the    white  substance;    b,   another  nerve- 

.     .               .                 £  fibre  with  nucleus.     In  both  these  nerve- 

1S  to  Say,  it  IS  continuous  trom  fibres  the  white  substance  is  stained  black 

end  to  end,  from    its    Origin   to  withosmic  acid,  and  the  axis-cylinder  is 

.  seen  running  as  an  uninterrupted  strand 

Its  termination.  through  the  centre  of  fibre,    c,  ordinary 

(2)  The     medullary    sheath  nerve-fibre  unstained ;  d,  e,  smaller  nerve- 

fibre ;  /,  varicose  nerve-fibre ;   g,  non-me- 

surrounding  the  axis-cylinder  duiiated  nerve-fibres. 
is  a  fatt}r,  semi-solid,  white  sub- 
stance, which  does  not  form  a  complete  tube,  but  at  tolerably 
regular  intervals  is  separated  into  segments ;  it  is   not  continu- 
ous from  end  to  end  like  the  axis-cylinder,  being  wanting  at 
the  origin  and  termination  of   the  nerve-fibre.     (We  may  look 
upon  the  axis-cylinder  as'the  live  or  naked  wire  of  the  fibre,  and 
the  white  sheath  as  the  isolating,  non-conducting  substance.) 

(3)  The  neurilemma  or  enclosing  sheath  is  a  thin  structure- 
less tube,  which  tightly  encloses  the  medullary  sheath  as  the 
sarcolemma  encloses  the  muscle-fibre. 

The  non-medullated  fibres  have  no  medullary  sheath  and  no 
neurilemma.  They  frequently  branch  as  the  medullated  fibres 
never  do  except  near  their  termination. 

The  nerve-fibres  are  gathered  into  cords  of  variable  size  to 
form  the  nerves.  These  cords  are  called  funiculi.  Each  f uni- 
culus  has  its  own  sheath  of  connective  tissue.  If  a  nerve  is 
small,  it  may  consist  of  one  funiculus,  but  in  larger  nerves  sev- 
eral funiculi  are  united  by  connective  tissue  into  one  large  cord 


202 


ANATOMY  FOB  NUKSES.       [CHAP.  XVIII. 


or  nerve,  the  whole  nerve  being  covered  by  a  dense  fibrous 
sheath  of  connective  tissue. 

Besides  connecting  the  funiculi,  the  connective  tissue  serves 
to  convey  the  blood-vessels  and  lymphatics  distributed  to  the 
nerve-fibres. 

The  nerves  that  conduct  nervous  impulses  towards  the  nerve- 
centres  are  called  afferent  or  sensory  nerves,  while  those  that 


FIG.  117.  —  SECTION  OF  THE  INTERNAL  SAPHENOTJS  NERVE.  Stained  in  osmic 
acid  and  subsequently  hardened  in  alcohol.  Drawn  as  seen  under  a  very  low  magni- 
fying power.  (G.  A.  S.)  ep,  epineurium,  or  general  sheath  of  the  nerve,  consisting 
of  connective  tissue  separated  by  cleft-like  areolae,  which  appear  as  a  network  of 
clear  lines,  with  here  and  there  fat-cells,/,/,  and  blood-vessels,  v. ;  per,  perineurium, 
or  particular  sheath  of  funiculus;  end,  endoneurium,  or  connective  tissue  within 
f  uniculus,  embedded  in  which  are  seen  the  cut  ends  of  the  medullated  nerve-fibres. 
The  fat-cells  and  the  nerve-fibres  are  darkly  stained  by  the  osmic  acid. 

transmit  nervous  impulses  from  the  nerve-centres  towards  the 
periphery  are  termed  efferent  or  motor  nerves.  Both  afferent 
and  efferent  fibres  may  run  in  the  same  sheath. 

The  nervous  system.  —  The  great  nerve-centre  of  the  body  is 
the  cerebro-spinal  centre  or  axis,  consisting  of  the  brain  and 
spinal  cord.  The  nerves  arising  from  this  centre  extend  from 
thence  through  the  body  to  the  muscles,  sensible  parts,  and 


CHAP.  XVIIL]        THE  NERVOUS    SYSTEM.  203 

other  organs,  forming  the  mediums  of  communication  between 
these  distant  parts  and  the  great  nerve-centre. 

Connected  with  the  nerves  in  various  situations  are  smaller 
nerve-centres,  called  ganglia.  A  series  of  these  ganglia,  joined 
together  by  nervous  bands,  form  two  large  chains  on  either  side 
of  the  vertebral  column, 
extending  from  the  base 
of  the  cranium  to  the 
coccyx.  These  ganglia, 
with  their  nerves,  are 
generally  called  the  sym- 
pathetic system,  and  it  is 
usual  to  speak  of  the 
nervous  system  as  consist- 
ing of  the  cerebro-spinal 
system  and  of  the  sympa- 
thetic system. 

For  convenience  of  de- 
scription, we  will  divide 
the  cerebro-spinal  system 
into  — 

(1)  Brain     and    cranial 

nerves. 

(2)  Spinal  cord  and  spi- 

nal nerves. 

Brain  and  cranial  nerves. 
-The  brain,  the  most 
complex  and  largest  mass 
of  nervous  tissue  in  the 
body,  is  contained  in  the 
complete  bony  cavity  FlG.  118.  _  DlAGRAM  ILLUSTRATING~THE  GEN- 
formed  by  the  bones  of  ERAL  ARRANGEMENT  OF  THE  CEREBRO-SPINAL 

SYSTEM. 

the  cranium.     It  is  cov- 
ered by  three  membranes  (also  named  meninges),— the  dura 
mater,  pia  mater,  and  arachnoid. 

The  dura  mater,  a  dense  membrane  of  fibrous  connective 
tissue,  lines  the  bones  of  the  skull,  forming  their  internal  perios- 
teum, and  covers  the  brain.  It  sends  numerous  prolongations 
inwards  for  the  support  and  protection  of  the  different  parts  of 


204 


ANATOMY   FOR,   NURSES.        [CHAP.  XVIII. 


the  brain;  it  also  forms  sheaths  for  the  nerves  passing  out  of  the 

skull.     It  ma}'  be  called  the  protective  membrane. 

The  pia  mater  is  a  delicate  membrane  of  connective  tissue, 

containing  an  exceedingly  abundant  network  of  blood  and 
lymph  vessels.  It  dips  down  into  all  the 
crevices  and  depressions  of  the  brain, 
carrying  the  blood-vessels  which  go  to 
every  part.  It  may  be  called  the  vascular 
or  nutritive  membrane. 

The  arachnoid  is  a  delicate  membrane 
which  is  placed  outside  the  pia  mater.  It 
passes  over  the  various  eminences  arid  de- 
pressions on  the  surface  of  the  brain,  and 
does  not  dip  down  into  them  like  the  pia 
mater.  Beneath  it,  between  it  and  the 
pia  mater,  is  space  (sub-arachnoid  space) 
in  which  is  a  certain  amount  of  fluid.  The 
sub-arachnoid  space  at  the  base  of  the  brain 
is  of  considerable  size,  and  contains  a  large 
amount  of  this  clear  limpid  fluid,  called  the 
cerebro-spinal  fluid.  This  fluid  probably 
acts  as  a  sort  of  protective  water-cushion  to 
the  delicate  nervous  structure,  and  pre- 
vents the  effects  of  concussions  communi- 
cated from  without. 

The  brain  is  a  semi-soft  mass  of  white 
and  gray  matter.  The  white  matter  con- 
sists of  very  small,  medullated  nerve-fibres, 
running  in  various  directions,  and  sup- 
ported by  a  delicate  connective  tissue 
FIG.  119.— SIDE  VIEW  framework.  The  gray  matter  consists  of 

OF  THE  BRAIN  AND  SPI-  ceus    an(j  fine  Rray  fibres,  also  supported 

NAL  CORD  IN  PLACE.    The  . 

parts  which  cover  the  cere-   by  Connective  tissue. 

bro-spinal  centre  are    re-         The  bmin  ig  divided   into   four  principal 

moved.  *  -1- 

parts:  the  cerebrum,  the    cerebellum,  the 
pons  Varolii,  and  the  medulla  oblongata. 

The  medulla  oblongata  is  a  continuation  of  the  spinal  cord, 
which,  on  passing  into  the  cranial  cavity  through  the  foramen 
magnum,  widens  into  an  oblong-shaped  mass.  It  is  directed 
backwards  and  downwards,  its  anterior  surface  resting  on  a 


CHAP.  XVIII.]        THE   NEKVOUS    SYSTEM.  205 

groove  in  the  occipital  bone,  and  its  posterior  surface  forming 
the  floor  of  a  cavity  between  the  two  halves  or  hemispheres  of 
the  cerebellum.  The  cavity,  called  the  fourth  ventricle,  is  an 
expanded  continuation  of  a  tiny  central  canal  which  runs 
throughout  the  whole  length  of  the  spinal  cord. 

The  cerebellum,  or  little  brain,  overhangs  the  fourth  ventricle. 
It  is  of  a  flattened  oblong  shape,  and  measures  from  three  and  a 
half  inches  to  four  inches  transversely,  arid  from  two  to  two  and 
a  half  inches  from  before  backwards.  It  is  divided  in  the  middle 


FIG.  120.  — THE  BASE  OF  THE  BRAIN.  1,  longitudinal  fissure;  2,  2,  anterior  lobes 
of  cerebrum  ;  3,  olfactory  bulb  ;  7,  optic  commissure;  9,  3rd  nerve  ;  11,  4tb  nerve  ; 
13,  5tb  nerve  ;  14,  crura  cerebri ;  15,  Oth  nerve ;  16,  pons  Varolii ;  17,  7th  nerve  ;  19, 
8th  nerve;  20,  medulla  oblongata  ;  21,  9th  nerve;  23,  10th  nerve;  25,  llth  nerve; 
27,  12th  nerve;  28,  2i),  30,  31,  32,  cerebellum. 

line  into  two  halves  or  hemispheres  by  a  central  depression, 
each  half  being  subdivided  by  fissures  into  smaller  portions  or 
lobes.  The  surface  of  the  cerebellum  is  traversed  by  numerous 
curves  or  furrows,  which  vary  in  depth.  In  the  medulla  ob- 
longata, the  gray  matter  is  placed  in  the  interior,  and  the  white 
on  the  exterior;  in  the  cerebellum,  the  gray  is  on  the  outside, 
and  the  white  within. 

The  pons  Varolii,  or  bridge  of  Varolius,  lies  in  front  of  the 
medulla  oblongata.     It  consists  of  alternate  layers  of  transverse 


206  ANATOMY  FOB,   NURSES.        [CHAP.  XVIII. 

and  longitudinal  white  fibres,  intermixed  with  gray  matter. 
The  transverse  fibres  come  mainly  from  the  cerebellum,  and 
serve  to  join  its  two  halves.  The  longitudinal  fibres  come  from 
the  medulla  oblongata.  This  bridge  is  a  bond  of  union  between 
the  cerebrum,  cerebellum,  and  medulla  oblongata. 

The  cerebrum  is  by  far.  the  largest  part  of  the  brain.  It  is 
egg-shaped  or  ovoidal,  and  fills  the  whole  of  the  upper  portion 
of  the  skull.  It  is  almost  completely  divided  by  the  median 
fissure  into  two  hemispheres,  the  two  halves,  however,  being 
connected  in  the  centre  by  a  broad  transverse  band  of  white 
fibres,  called  the  corpus  callosum.  Each  half  is  subdivided  into 
lobes. 

The  longitudinal  fibres  of  the  medulla  oblongata,  passing 
through  the  pons  Varolii,  become  visible  in  front  of  the  bridge 
as  two  broad,  diverging  bundles.  These  two  bundles  form  what 
are  called  the  crura  cerebri^  or  pillars  of  the  brain,  and  are  situ- 
ated on  the  under  surface  of  each  hemisphere.  Between  the 
crura  cerebri  is  a  narrow  passage  (aqueduct  of  Sylvius)  lead- 
ing from  the  fourth  ventricle  into  a  smaller  cavity  called  the 
third  ventricle.  In  each  side  wall  of  the  third  ventricle  is  an 
opening  (foramen  of  Monro)  which  leads  into  two  large  cavi- 
ties, the  lateral  ventricles,  and  which  occupy  the  centre  of  each 
half  of  the  cerebrum.  (It  will  be  seen  from  the  above  descrip- 
tion that  the  cavities  in  the  centre  of  the  brain  are  continuous 
with  the  central  canal  in  the  spinal  cord,  and  also  that  fibres 
from  the  cord  pass  into  the  centre  of  the  cerebrum.)  Forming 
the  floors  of  the  ventricles,  lodged  in  the  crura  cerebri,  and 
scattered  in  their  neighbourhood,  are  irregularly  shaped  masses 
of  gray  matter,  intricately  connected  with  one  another  and  with 
the  gray  matter  in  the  medulla  oblongata.  The  surface  of  the 
cerebral  hemispheres  is  folded,  the  folds  or  convolutions  being 
deeper  and  more  numerous  in  some  brains  than  others:  the 
whole  of  the  convoluted  surface  is  composed  of  gray  matter 
arranged  in  several  layers  of  cells  and  fibres. 

The  whole  brain  appears  to  consist  of  a  number  of  isolated 
masses  of  gray  matter  —  some  large,  some  small  —  connected 
together  by  a  multitude  of  fibres  of  white  matter  arranged  in 
perplexing  intimacy.  But  a  general  arrangement  may  be  recog- 
nized. The  numerous  masses  of  gray  matter  in  the  interior  of 
the  brain  may  be  looked  upon  as  forming  a  more  or  less  contin- 


CHAP.  XVIII.]        THE   NERVOUS   SYSTEM.  207 

uous  column,  arid  as  forming  the  core  of  the  central  nervous 
system,  while  around  it  are  built  up  the  great  mass  of  the  cere- 
brum and  the  smaller  mass  of  the  cerebellum.  This  central 
core  is  connected  by  various  ties  with  the  spinal  cord,  besides 
being,  as  it  were,  a  continuation  of  the  gray  matter  in  the 
centre  of  the  cord.  It  is  also  connected  at  its  upper  end,  by 
numberless  fibres,  to  the  gray  matter  on  the  surface  of  the  cere- 
brum. 

The  different  masses  of  gray  matter  being  so  closely  asso- 
ciated and  connected  with  one  another,  it  will  be  seen  that  it 
becomes  a  very  difficult  matter  to  assign  definite  functions  to 
definite  areas.  Of  late  years,  however,  a  great  deal  has  been 
accomplished  in  this  direction,  and  it  has  become  possible  to 
locate  the  centres  that  preside  over  the  organs  of  speech,  sight, 
hearing,  etc.,  and  over  the  movement  of  muscles  in  any  part 
of  the  body.  Owing  to  the  crossing  or  decussation  of  fibres  in 
the  medulla  oblongata,  injuries  to  nerve-centres  on  the  right 
side  of  the  brain  will  affect  the  left  side  of  the  body,  below  the 
decussation. 

The  average  weight  of  the  brain  in  the  male  is  49|-  oz. ;  in 
the  female,  44  oz.  It  appears  that  the  weight  of  the  brain  in- 
creases rapidly  up  to  the  seventh  year,  more  slowly  to  between 
sixteen  and  twenty,  and  still  more  slowly  to  between  thirty  and 
forty,  when  it  reaches  its  maximum.  Beyond  this  age  the  brain 
diminishes  slowly  in  weight,  about  an  ounce  every  ten  years. 
The  size  of  the  brain  bears  a  general  relation  to  the  capacity  of 
the  individual.  Cuvier's  brain  weighed  rather  more  than  64  oz., 
while  the  brain  of  an  idiot  seldom  weighs  more  than  23  oz.  The 
number  and  depth  of  the  cerebral  convolutions  also  bear  a  close 
relation  to  intellectual  power ;  babies  and  idiots  have  few  and 
shallow  folds,  while  the  brains  of  men  of  intellect  are  always 
markedly  convoluted. 

The  cranial  nerves.  —  The  cranial  nerves,  twelve  in  number  on 
each  side,  arise  from  the  base  of  the  brain  and  medulla  oblon- 
gata (iride  Fig.  120),  and  pass  out  through  openings  in  the  base 
of  the  skull.  They  are  named  numerically  according  to  the 
order  in  which  they  pass  out  of  the  skull.  Other  names  are  also 
given  to  them  derived  from  the  parts  to  which  they  are  dis- 
tributed, or  from  their  functions.  Taken  in  their  order  from 
before  backwards,  they  are  as  follows :  — 


208  ANATOMY   FOR   NURSES.        [CHAP.  XVIII. 

1.  Olfactory.  7.  Facial. 

2.  Otpic.  8.  Auditory. 

3.  Motor  oculi.  9.  Glosso-pharyngeal. 

4.  Pathetic.  10.  Pneumo-gastric. 

5.  Trifacial.  11.  Spinal-accessory. 

6.  Abducens.  12.  Hypo-glossal. 

The  first  or  olfactory  nerve  is  the  special  nerve  of  the  sense 
of  smell.  It  arises  by  three  roots  from  the  interior  of  the  brain, 
and  sends  numerous  fibres  through  the  perforated  plate  of  the 
ethmoid  bone,  to  be  distributed  to  the  mucous  membrane  lining 
the  nasal  chamber. 

The  second  or  optic  nerve  is  the  special  nerve  of  the  sense  of 
sight.  It  enters  the  orbit  and  is  distributed  to  the  interior  of 
the  eyeball.  Before  entering  the  orbit  the  nerve  is  connected 
with  its  fellow  of  the  opposite  side  by  a  band  or  commissure, 
and  from  this  union  it  may  be  traced  back  along  the  optic  tract 
to  its  deep  origin  in  the  central  gray  matter  of  the  brain. 

The  third  or  motor  oculi  nerve  is  the  chief  mover  of  the  eye ; 
it  supplies  all  the  muscles  of  the  eye  with  the  exception  of  the 
superior  oblique  and  external  rectus.  Its  origin  may  be  traced 
back  to  the  gray  matter  in  the  medulla  oblongata. 

The  fourth  or  pathetic  nerve,  the  smallest  of  the  cranial 
nerves,  supplies  the  superior  oblique  muscle  of  the  eye.  It 
arises  close  to  the  third  nerve. 

The  fifth  or  trifacial  nerve  is  the  largest  of  the  cranial  nerves. 
It  arises  by  two  roots,  —  a  posterior  or  sensory,  and  an  anterior 
or  motor.  The  posterior  root  is  larger  than  the  anterior,  and 
has  a  ganglion  developed  on  it.  The  fibres  from  the  two  roots 
coalesce  into  one  trunk,  and  then  subdivide  into  three  large 
branches:  the  ophthalmic,  the  superior  maxillary,  and  the 
inferior  maxillary.  The  ophthalmic  branch  is  the  smallest,  and 
is  a  sensory  nerve.  It  supplies  the  eyeball,  the  lachrymal  gland, 
the  mucous  lining  of  the  eye  and  nose,  and  the  skin  and  mus- 
cles of  the  eyebrow,  forehead,  and  nose.  The  superior  maxil- 
lary, the  second  division  of  the  fifth,  is  also  a  sensory  nerve  and 
supplies  the  skin  of  the  temple  and  cheek,  the  upper  teeth,  and 
the  mucous  lining  of  the  mouth  and  pharynx.  The  inferior 
maxillary  is  the  largest  of  the  three  divisions  of  the  fifth,  and  is 
both  a  sensory  and  motor  nerve.  It  sends  branches  to  the  tem- 
ple and  the  external  ear;  to  the  teeth  and  lower  jaw;  to  the 


CHAP.  XVIII.]        THE  NERVOUS   SYSTEM.  209 

muscles  of  mastication :  it  also  supplies  the  tongue  with  a 
special  nerve  (the  lingual)  of  the  sense  of  taste. 

The  sixth  or  abducens  nerve  supplies  the  external  rectus 
muscle  of  the  eye. 

The  seventh  or  facial  nerve  is  the  motor  nerve  of  all  the 
muscles  of  expression  in  the  face :  it  also  supplies  some  muscles 
of  the  neck  and  ear.  It  arises  close  to  the  sixth  nerve  on  the 
floor  of  the  fourth  ventricle. 

The  eighth  or  auditory  nerve  is  the  special  nerve  of  the  sense 
of  hearing,  being  distributed  exclusively  to  the  internal  ear. 

The  ninth  or  glosso-pharyngeal  nerve  is  distributed,  as  its 
name  indicates,  to  the  tongue  and  pharynx,  being  the  nerve  of 
sensation  to  the  mucous  membrane  of  the  pharynx,  of  motion 
to  the  pharyngeal  muscles,  and  the  special  nerve  of  taste  to  part 
of  the  tongue. 

The  tenth  or  pneumogastric  nerve  has  a  more  extensive  dis- 
tribution than  any  of  the  other  cranial  nerves,  passing  through 
the  neck  and  thorax  to  the  upper  part  of  the  abdomen.  It 
contains  both  motor  and  sensory  fibres.  It  supplies  the  organs 
of  voice  and  respiration  with  motor  and  sensitive  filaments; 
and  the  pharynx,  oasophagus,  stomach,  and  heart  with  motor 
fibres.  This  nerve  is  sometimes  spoken  of  as  the  par  vagus. 

The  eleventh  or  spinal-accessory  nerve  consists  of  two  parts : 
one,  the  spinal  portion,  and  the  other,  the  accessory  portion  to 
the  tenth  nerve.  It  is  a  motor  nerve  supplying  certain  muscles 
of  the  neck.  It  differs  from  the  other  cranial  nerves  in  arising 
from  the  spinal  cord,  but  it  leaves  the  skull  by  the  same  aper- 
ture as  the  pneumogastric  and  glosso-pharyngeal. 

The  twelfth  or  hypoglossal  nerve  is  the  motor  nerve  of  the 
tongue. 

All  the  cranial  nerves,  with  the  exception  of  the  two  first 
pairs  and  the  spinal  accessory,  arise  from  the  gray  matter  in  the 
medulla  oblongata,  and  any  injury  to  the  medulla  oblongata  is 
attended  with  the  most  serious  results,  while  extensive  injury 
arrests  the  respiratory  processes  and  causes  instant  death. 

It  will  be  observed  that  of  the  twelve  pairs  of  cranial  nerves, 
four,  arid  a  part  of  a  fifth,  are  distributed  to  the  eye ;  viz.  the  optic, 
motor  oculi,  pathetic,  abducens,  and  the  ophthalmic  branch  of 
the  fifth.  The  ear  has  one  special  nerve,  the  auditory,  and  is 
sparingly  supplied  with  motor  and  sensitive  fibres  from  other 


210  ANATOMY   FOE   NUKSES.        [CHAP.  XVIII. 

nerves.  The  nose  has  also  one  special  nerve,  the  olfactory,  and 
is  more  abundantly  supplied  than  the  ear,  with  motor  and  sen- 
sitive fibres  from  other  nerves.  The  tongue  has  two  special 
branch  nerves  of  taste,  —  the  lingual,  a  branch  of  the  fifth,  and 
the  glossal,  a  branch  of  the  ninth:  it  has  also  its  own  motor 
nerve,  the  hypoglossal. 

The  spinal  cord  and  spinal  nerves.  —  The  spinal  cord  is  a 
column  of  gray  and  white  soft  substance,  extending  from  the 
top  of  the  spinal  canal,  where  it  is  continuous  with  the  brain,  to 
about  the  second  lumbar  vertebra,  where  it  tapers  off  into  a  fine 
thread.  Before  its  termination  it  gives  off  a  number  of  fibres 
which  form  a  tail-like  expansion,  called  the  cauda  equina. 

Like  the  brain,  the  spinal  cord  is  protected  and  nourished  by 
three  membranes.  These  membranes  have  the  same  names  and 
practically  exercise  the  same  functions  as  those  enveloping  the 
brain.  The  dura  mater  is  not  attached  to  the  walls  of  the  spinal 
canal,  being  separated  from  them  by  a  certain  quantity  of  areo- 
lar  and  adipose  tissue  and  a  network  of  veins.  Therefore,  the 
spinal  cord  does  not  fit  closely  into  the  spinal  canal,  as  the 
brain  does  in  the  cranial  cavity,  but  is,  as  it  were,  suspended 
within  it.  It  diminishes  slightly  in  size  from  above  downwards, 
with  the  exception  of  presenting  two  enlargements  in  the 
cervical  and  dorsal  regions.  It  is  usually  from  sixteen  to 
seventeen  inches  long,  and  has  an  average  diameter  of  three- 
fourths  of  an  inch.  The  spinal  cord  is  almost  completely 
divided  into  lateral  halves  by  an  anterior  and  posterior  fissure, 
the  anterior  fissure  dividing  it  in  the  middle  line  in  front,  and 
the  posterior  fissure,  in  the  middle  line  behind.  In  conse- 
quence of  the  presence  of  these  fissures,  only  a  narrow  bridge 
of  the  substance  of  the  cord  connects  its  two  halves,  and  this 
bridge  is  traversed  throughout  its  entire  length  by  a  minute  cen- 
tral canal, — the  canalis  centralis.  On  making  a  transverse  sec- 
tion of  the  spinal  cord,  the  gray  matter  is  seen  to  be  arranged  in 
each  half  in  the  form  of  a  half-moon  or  crescent,  with  one  end 
bigger  than  the  other,  and  with  the  concave  side  turned  out- 
wards. The  convex  sides  of  the  gray  matter  in  each  half 
approach  one  another,  and  are  joined  by  the  isthmus  or  bridge 
which  contains  the  central  canal.  The  tips  of  each  crescent 
are  called  its  horns  or  cornua,  the  front  or  anterior  cornua 
being  thicker  and  larger  than  the  posterior.  The  white  mat- 


CHAP.  XVIII.]        THE   NERVOUS    SYSTEM. 


211 


ter  of  the  cord  is  arranged  around  and  between  the  gray  matter, 
the  proportion  of  gray  and  white  matter  varying  in  different 
regions  of  the  cord.  The  white  matter,  as  in  the  brain,  is  com- 
posed of  medullated  nerves,  and  the  gray  matter  of  nerve-cells 


FIG.  121.  —  TRANSVERSE  SECTIONS  OF  THE  SPINAL  CORD  AT  DIFFERENT  LEVELS. 
(Gowers.)  (Twice  the  natural  size.)  The  letters  and  numbers  indicate  the  position  of 
each  section :  Ca,  at  level  of  coccygeal  nerve ;  Sac4,  of  4th  sacral ;  Is,  at  third  lum- 
bar, and  so  on.  The  gray  substance  is  shaded  dark,  and  the  nerve-cells  within  it  are 
indicated  by  dots. 

and  fine  gray  fibres,  all  held  together  and  supported  by  delicate 
connective  tissue.  The  majority  of  the  nerves  run  in  a  longi- 
tudinal direction. 

There  is  no  real  division  between  the  brain  and  spinal  cord, 


212 


ANATOMY  FOR   NURSES.        [CHAP.  XVIII. 


the  brain  being  built  upon  the  cord,  and  together  they  form  the 
great  nerve-centre  or  axis — the  cerebro-spinal — which,  by  means 
of  the  cranial  and  spinal  nerves,  is  placed  in 
connection  with  all  parts  of  the  body.  Al- 
though the  gray  matter  in  the  spinal  cord 
is  intimately  connected  with  the  gray  matter 
in  the  brain,  it  has  some  functions  indepen- 
dent of  the  brain,  which  will  be  described  in 
connection  with  the  spinal  nerves. 

The  spinal  nerves.  —  There  are  thirty-one 
pairs  of  spinal  nerves,  arranged  in  the  follow- 
ing groups,  and  named  from  the  regions 
through  which  they  pass.  They  are :  — 

Cervical 8  pairs 

Dorsal 12     " 

Lumbar 5     " 

Sacral 5     " 

Coccygeal 1  pair 

The  spinal  nerves  pass  out  of  the  spinal 
canal  through  the  intervertebral  foramina, 
the  openings  between  the  vertebree  spoken 
of  in  the  lesson  on  the  bones  of  the  spine. 

Each  spinal  nerve  has  two  roots,  an  anterior 
root  and  a  posterior  root.  The  fibres  con- 
nected with  these  two  roots  are  collected  into 
one  bundle,  and  form  one  nerve  just  before 
leaving  the  canal  through  the  intervertebral 
openings.  Before  joining  to  form  a  common 
trunk,  the  fibres  connected  with  the  posterior 
root  present  an  enlargement,  this  enlargement 
being  due  to  a  ganglion,  or  small  nerve 
centre.  The  fibres  of  the  anterior  root  arise 

nal    cervical    nerves;     from   tfo   gray  matter   [n   the   anterior   COH1U, 


FIG.  122.— BASE  OF 
BRAIN,  SPINAL  CORD, 
AND  SPINAL  NERVES. 
V,  IX,  cranial  nerves; 
a,  6,  c,  d,  sympathetic 
ganglia;  C'M,  spi- 


Di-12,  spinal    dorsal 
nerves;   Z,*-5,  spinal 
lumbar  nerves ;  S  M 
sacral ;  6,  coccygeal. 


and  appear  for  the  most  part  to  be  direct  pro- 
longations from  the  nerve-cells  there.  The 
fibres  of  the  posterior  root,  on  the  other 
hand,  appear  to  arise  in  most  cases  from  the  cells  in  the  ganglion, 
and  to  grow  into  the  nerve-centres  forming  the  gray  matter  in  the 
posterior  cornu.  The  fibres  growing  from  the  anterior  root  are 


CHAP.  XVIII.]        THE   NERVOUS   SYSTEM. 


213 


efferent  fibres,  and  convey  nervous  impulses  from  the  spinal 
cord  to  the  periphery.  The  fibres  growing  into  the  posterior 
root  are  afferent  fibres,  and  convey  nervous  impulses  from  the 
periphery  to  the  spinal  cord.  The  afferent  fibres  usually  con- 
vey sensory  impressions,  and  the  efferent  motor  impulses. 

The  thirty-one  pairs  of  spinal  nerves,  containing  within  the 
one  sheath  both  afferent  and  efferent  fibres,  issue  at  regular 
intervals  from  the  spinal  canal,  and  are  distributed  to  all  parts 
of  the  body,  the 
efferent  or  motor 
fibres  being  distrib- 
uted to  the  muscular 
tissue,  and  causing 
contraction  of  the 
muscles ;  the  afferent 
or  sensory  fibres  end- 
ing commonly  in  the 
skin,  and  conveying 
nervous  impulses  to 
the  nerve  -  centres 
which  give  rise  to 
sensation. 

The    nervous    im- 
pulses transmitted  by 


the  afferent  nerves  to 
the    spinal   cord   are 


the  cord  to  the  brain, 
and  the    nervous  im- 


FIG.    123.  —  SECTIONS    OF    SPINAL    CORD    AND 
NERVE-ROOTS.    A,  anterior  view;  B,  side  view;  C, 

USUallv  forwarded  bv      transverse  section;  J),  two  isolated  roots  of  a  spinal 
J  *       nerve.    1,  anterior  fissure;  2,  posterior  fissure;  3, 

groove  formed  by  anterior  roots;  4,  groove  formed 
by  posterior  roots ;  5,  fibres  of  anterior  root ;  6, 
fibres  of  posterior  root;  6,  ganglion  on  posterior 

pulses  sent  out  along     root, 
the  efferent  fibres  to 

the  muscles  are  also  commonly  transmitted  by  the  spinal  cord 
from  the  brain.  And  if  the  spinal  cord  be  so  injured  as  to 
practically  sever  its  connection  with  the  brain,  it  will  be  found 
that  paralysis  and  insensibility  of  the  body  below  the  injury 
will  ensue,  showing  conclusively  that,  severed  from  the  brain, 
the  ability  of  the  spinal  cord  to  give  rise  to  sensation,  or  to 
control  muscular  contractions,  is  seriously  impaired.  Yet  the 
gray  matter  in  the  spinal  cord  has  a  certain  power  of  its  own, 
for  after  the  cord  has  been  severed  from  the  brain,  spasmodic 


214 


ANATOMY  FOR   NURSES.         [CHAP.  XVIII. 


contraction  of  muscles  can  be  made  to  take  place.     The  appli- 
cation of  stimuli  to  the  afferent  nerve-fibres  ending  in  a  portion 

of  the  skin  will  set  up 
changes  in  the  fibres, 
which  changes  will  be 
transmitted  by  them  to 
the  gray  matter  in  the 
posterior  root  of  the 
spinal  cord.  These 
changes  or  nervous  im- 
pulses, instead  of  being 
sent  up  the  cord  to  the 
seat  of  sensation  in 
the  brain,  and  thus 
giving  rise  to  sensa- 
tion, are  transmitted 
to  the  gray  matter  in 
the  anterior  root  of 
the  cord,  and  conveyed 
thence  by  the  efferent 
fibres  to  the  muscles, 
which  they  cause  to 
contract.  This  power 
of  transforming  an  af- 
ferent into  an  efferent 
impulse  is  termed  the 
reflex  power  of  the 
spinal  cord. 

The  sympathetic  sys- 
tem.— The  sympathetic 
system  consists  of  a 
double  chain  of  gan- 
glia, placed  on  each 
side  of  the  spinal 
column,  and  united 
with  each  other  by 

Fio.  124.  —  GENERAL  VIEW  OF  THE  SYMPATHETIC  longitudinal  filaments. 

SYSTEM.    1,  2,  3,  cervical  ganglia;   4,  1st  thoracic  T,           ,,      .      f, 

ganglion;  5,  1st  lumbar  ganglion;  6,  7,  sacral  gang-  ln6 

lion:  <»,  9,  cardiac  nerves;    13,  branch  of  pneumo-  Ha     are     Smaller     than 

gastric   nerve  ending  in  semi-lunar   ganglion-    14  ,1            •      ,1       i       •            j 

epi-astric  plexus.  '  those  in  the  brain  and 


CHAP.  XVIII.]        THE   NERVOUS   SYSTEM. 


215 


spinal  cord,  and  the  fibres 'that  arise  from  them  are  mostly  of 
the  non-medullated  variety. 

These  ganglia  and  nerves  do  not  form  an  independent  ner- 
vous system,  for  each  ganglion  is  connected  by  motor  and  sensi- 
tive fibres  with  the  cerebral  system.  The  sympathetic  nerves  are 
distributed  to  the  viscera  and  blood-vessels,  of  which  the  move- 
ments are  involuntary,  and  the  general  sensibility  obtuse.  They 
form  networks  or  plexuses  upon  the  heart,  about  the  stomach, 
and  other  viscera  in  the  trunk ;  they  also  enter  the  cranium, 
send  branches  to  the  organs  of  special  sense,  and,  in  particu- 
lar, influence  the  pupil  of  the  eye.  Their  most  important 
distribution,  however,  is  in  connection  with  the  blood-vessels. 
They  form  plexuses  around  the  vessels, 
especially  the  arteries,  and  send  fibres 
to  terminate  in  the  involuntary  mus- 
cular tissue  of  which  the  walls  of 
these  tubes  are  largely  composed.  The 
nerves  thus  distributed  are  called 
"  vaso-motor  "  nerves. 

The  unity  of  the  nervous  system. — 
From  the  foregoing  description  of  the 
nervous  system,  it  is  clear  that  it  forms 
one  continuous  whole,  through  the 
agency  of  which  all  the  varied  activi-  FlG-  125-  —  NERVE  ENDING 

,,      .        .      ,  ..     IN    MUSCULAR    FIBRE    OF    A 

ties  ol  the  body  are  controlled  and  LIZARD.  (Kuhne.)  The  end- 
regulated.  We  may  compare  it  to  a  plate,  or  motorial  ending  of  the 

'  axis-cylinder,  is  seen  sideways. 

telegraphic  system,  the  central   office 

of  which  would  represent  the  brain  and  spinal  cord,  the  more 
important  sub-offices  the  sympathetic  ganglia,  and  the  minor 
offices  the  isolated  ganglia ;  while  the  telegraph  wires,  directly 
or  indirectly  uniting  all,  would  correspond  to  the  nerves.  And 
just  as  a  message  started  along  some  outlying  wire  may  be 
transmitted  to  a  central  office,  and,  according  to  the  informa- 
tion received,  will  be  stopped  there,  or  sent  to  some  other 
centres  to  be  forwarded  by  them  in  one  direction,  in  two  direc- 
tions, or  all  over  the  country,  —  so  may  a  nervous  impulse  reach- 
ing the  brain  merely  excite  some  change  in  the  brain  itself,  or 
be  sent  out  from  thence  along  the  nerve-trunks  to  excite  activi- 
ties in  various  parts  of  the  body. 

Peripheral  termination  of  nerves.  —  The  nerves  have  their  origin 


216  ANATOMY  FOE,  NUKSES.        [CHAP.  XVIII. 

in  the  gray  matter  of  the  brain,  in  the  spinal  cord,  and  in  vari- 
ous ganglia ;  their  termination,  or  peripheral  distribution,  is  not 
so  easy  to  determine. 

All  nerves,  medullated  or  non-medullated  alike,  in  approaching 
their  final  distribution,  divide ;  that  is,  the  numerous  strands  or 
fibres  which  go  to  make  up  a  nerve  separate  from  one  another. 
If  we  follow  a  fibre,  we  find,  if  it  is  a  medullated  one,  that  the 


FIG.  126.  —  SECTION  OF  SKIN  SHOWING  TACTILE  CORPUSCLE  IN  PAPILLA,    d, 
nerve  passing  up  to  tactile  corpuscle ;  t,  tactile  corpuscle. 

sheaths  enclosing  it  gradually  disappear,  and  finally  the  axis 
cylinder  itself  splits  into  its  component  fibrils.  These  fibrils 
may  terminate  in  invisible  threads,  as  between  the  cells  in  the 
Malpighian  layer  of  epidermis,  or  they  may  terminate  in  special 
end  organs,  such  as  the  tactile  bodies  in  the  papillae  of  the 
skin,  the  round-end  bulbs  in  the  conjunctiva,  the  motorial  rami- 
fications in  the  muscular  fibres,  and  in  other  ways  too  numerous 
and  too  complicated  for  us  to  attempt  to  describe. 

Degeneration  and  regeneration  of  nerves-  — The  divided  ends  of  a 
nerve  that  has  been  cut  across  readily  reunite  by  cicatricial  tissue,  —  that  is 
to  say,  the  connective  tissue  framework  unites,  —  but  the  cut  ends  of  the 
fibres  themselves  do  not  unite.  On  the  contrary,  the  peripheral  or  severed 
portion  of  the  nerve  begins  to  degenerate,  the  medullary  sheath  breaks  up 
into  a  mass  of  fatty  molecules  and  is  gradually  absorbed,  and  finally  the 


CHAP.  XVIII.]       THE   NERVOUS   SYSTEM. 


217 


axis-cylinder  also  disappears.  In  regeneration,  the  new  fibres  grow  afresh 
from  the  axis-cylinders  of  the  central  end  of  the  severed  nerve-trunk,  and, 
penetrating  into  the  peripheral  end  of  the  trunk,  grow  along  this  as  the 
axis-cylinders  of  the  new  nerve,  each  axis-cylinder  becoming  after  a  time 


FIG.  127.— -END-BULBS  FROM  THE  HUMAN  CONJUNCTIVA.  (Longworth.)  A, 
ramification  of  nerve-fibres  in  the  mucous  membrane,  and  their  termination  in  end- 
bulbs,  as  seen  with  a  lens ;  B,  an  end-bulb  more  highly  magnified  ;  a,  nucleated  cap- 
sule ;  6,  core ;  c,  entering  fibre  branching,  and  its  two  divisions  passing  to  terminate 
in  the  core  at  d ;  C,  an  end-bulb  treated  with  osmic  acid,  showing  the  cells  of  the 
core  better  than  B. 


surrounded  with  a  medullary  sheath.  Restoration  of  function  in  the  nerve 
may  not  occur  for  several  months,  during  which  time  it  is  presumed  the  new 
nerve-fibres  are  slowly  finding  their  way  along  the  course  of  those  which 
have  been  destroyed. 


CHAPTER  XIX. 

THE  ORGANS  OF  SPECIAL  SENSE:  THE  SKIN,  THE  ORGAN  OF 
THE  SENSE  OF  TOUCH,  AND  OF  HEAT  AND  COLD;  THE 
TONGUE,  THE  ORGAN  OF  THE  SENSE  OF  TASTE ;  THE  NOSE, 
THE  ORGAN  OF  THE  SENSE  OF  SMELL;  THE  EAR,  THE 
ORGAN  OF  THE  SENSE  OF  HEARING;  THE  EYE,  THE  ORGAN 
OF  THE  SENSE  OF  SIGHT. 

OUR  sensations  are  both  varied  and  numerous,  and  arise  from 
within  and  from  without.  Sensations  arising  from  within  our- 
selves, such  as  feelings  of  fatigue,  hunger,  thirst,  restlessness, 
etc.,  and  to  which  we  can  assign  no  particular  place,  we  usually 
speak  of  under  the  name  of  diffuse  or  subjective  sensations. 
Sensations  produced  by  impressions  made  on  a  definite  part  of 
the  body,  and  only  excited  by  some  particular  influence  applied 
to  that  part  of  the  body,  we  usually  speak  of  under  the  name  of 
special  or  objective  sensations :  such  are  sensations  of  touch,  heat, 
and  cold,  of  taste  and  smell,  and  of  sound  and  light. 

Any  portion  of  the  body  to  which  a  sensation  is  thus  restricted 
is  called  a  sensory  organ,  and  of  these  special  sensory  organs 
there  are  five,  viz. :  — 

The  skin,  the  organ  of  the  sense  of  touch. 
The  tongue,  the  organ  of  the  sense  of  taste. 
The  nose,  the  organ  of  the  sense  of  smell. 
The  ear,  the  organ  of  the  sense  of  hearing. 
The  eye,  the  organ  of  the  sense  of  sight. 

In  order  to  be  conscious  of  any  sensation,  it  is  necessary  for 
the  end-organ  (that  is,  the  sensory  organ  which  receives  impres- 
sions) to  be  placed  in  communication  with  the  brain,  which  is 
the  seat  of  all  sensation.  If,  for  instance,  the  optic  nerve,  which 
is  the  medium  of  communication  between  the  visual  centre  in 
the  brain  and  the  end-organ,  the  eye,  be  destroyed,  the  indi- 

218 


CHAP.  XIX.]       ORGANS   OF   SPECIAL   SENSE.  219 

vidual  will  be  unable  to  see  with  that  eye.  In  thinking  of  the 
sensory  organs,  then,  we  must  remember  that  they  are  structures 
specially  modified  and  adapted  to  receive  certain  impressions, 
which  impressions,  when  conveyed  to  the  brain,  give  rise  to  definite 
sensations. 

The  sense  of  touch.  —  The  sense  of  touch,  as  also  the  sense  of 
heat  and  cold,  is  possessed  more  or  less  acutely  by  all  parts  of 
the  skin,  and  also  by  the  mucous  membrane,  or  internal  skin, 
lining  the  nose  and  mouth.  We  noted  in  the  lesson  on  the 
skin,  that  the  sense  of  touch  is  most  delicate  in  those  parts 
where  the  papillae  of  the  true  skin  are  most  abundant  and  con- 
tain the  special  nerve-endings  called  tactile  corpuscles,  as  in  the 
tips  of  the  fingers  and  toes  (vide  page  191).  The  feelings  of 
warmth  and  cold  are  also  caused  by  exciting  sensory  nerves  dis- 
tributed to  the  skin,  though  they  are  probably  distinct  from 
those  which  give  rise  to  the  sense  of  touch.  The  sense  of 
warmth  and  cold  varies  also  in  sensitiveness  in  different  parts 
of  the  body,  and  we  involuntarily  test  the  temperature  of  an 
iron  or  of  a  poultice  by  holding  it  to  the  cheek,  and  when  we 
are  cold  we  spread  the  palms  of  our  hands  to  the  fire. 

If  the  nerves  of  the  skin  are  unduly  stimulated  by  severe 
pressure,  or  by  exposure  to  extremes  of  heat  or  cold,  the  sense 
of  touch  and  of  temperature  is  lost  in  the  sense  of  pain.  This 
is  also  the  case  if  the  nerves  are  too  freely  exposed,  as  when 
the  epidermis  is  removed  by  blistering,  or  in  some  other  man- 
ner, and  the  skin  is  left  "raw." 

The  sense  of  taste.  —  The  special  organ  of  the  sense  of  taste  is 
the  tongue,  which  is  a  movable  muscular  organ  covered  with 
mucous  membrane.  The  mucous  membrane  closely  resembles 
the  skin  in  structure,  except  that  the  papillae  it  contains  are 
more  highly  developed.  The  papillae  project  as  minute  promi- 
nences and  give  the  tongue  its  characteristic  rough  appearance. 

Some  of  the  papillae  are  simple  and  resemble  those  found  in 
the  skin ;  the  remainder  are  compound,1  and  are  only  found  on 
the  surface  of  the  tongue.  Of  these  compound  papillae  there 
are  three  varieties.  The  largest,  the  circumvallate  papillce,  are 
about  eight  or  ten  in  number,  and  form  a  V-shaped  row  near  the 
root  of  the  tongue,  with  its  open  angle  turned  towards  the  lips. 

1  A  compound  papilla  is  one  large  one  bearing  several  smaller  ones  on  its  sur- 
face. 


220 


ANATOMY   FOR   NURSES.          [CHAP.  XIX. 


The  next  in  size  are  the  fungiform  papillce,1  found  principally  on 
the  tip  and  sides  of  the  tongue.  The  smallest  and  most  numer- 
ous are  the  filiform  papillce,  found  all  over  the  tongue,  excepting 
the  root,  and  bearing  on  their  free  surface  a  form  of  ciliated 
epithelium.  In  some  animals  the  hair-like  processes  on  the  fili- 


Fio.  128.  — THE  UPPER  SURFACE  OF  THE  TONGUE.     1,  2,  circumvallate  papillae; 
3,  fuiigil'orm  papillae ;  4,  filiform  papillae ;  6,  mucous  glands. 

form  papillae  are  horny  in  structure,  and  their  tongues  are  cor- 
respondingly roughened,  so  that  they  supplement  the  teeth  in 
the  bruising  and  crushing  of  food.  In  man  these  hair-like  pro- 

1  The  fungiform  papillae  resemble  fungi,  having  an  expanded  upper  portion 
resting  on  a  short,  thick  pedicle.  The  circumvallate  papillae  resemble  the 
fungiform,  except  that  they  are  surrounded  by  a  wall  of  smaller  papillae. 


CHAP.  XIX.]      OKGANS   OF   SPECIAL   SENSE.  221 

cesses  are  exceedingly  delicate,  and  seem  to  be  specially  con- 
nected with  the  sense  of  touch,  which  on  the  tip  of  the  tongue 
is  highly  developed,  and  which  serves  to  guide  the  tongue  in  its 
variable  and  complicated  movements. 

In  the  circumvallate,  some  of  the  fungiform  papillae,  and 
scattered  also  over  the  mucous  membrane  of  the  tongue  and 
soft-  palate,  are  little  clusters  of  cells  lying  in  cavities  of  the 
epithelium,  called  taste-buds.  The  bases  of  these  cell-clusters, 
or  taste-buds,  are  supplied  with  nerve-fibres,  and  it  is  surmised 
that  they  are  more  specially  connected  with  the  sense  of  taste 
than  the  other  portions  of  the  mucous  membrane  covering  the 
tongue. 

The  special  nerves  of  the  sense  of  taste  distributed  to  the 
tongue  are  the  glosso-pharyngeal,  or  ninth  nerve,  and  the  lin- 
gual or  gustatory,  a  branch  of  the  fifth  nerve.  The  former 
supplies  the  back  of  the  tongue,  and  section  of  it  destroys  taste 
in  that  region ;  the  latter  is  distributed  to  the  front  of '  the 
tongue,  and  section  of  it,  similarly,  deprives  the  tip  of  the 
tongue  of  taste. 

We  often  confound  taste  with  smell.  Substances  which  have 
a  strong  odor,  such  as  onions,  are  smelled  as  we  hold  them  in  our 
mouths ;  and  if  our  sense  of  smell  is  temporarily  suspended,  as 
it  sometimes  is  by  a  bad  cold  in  the  head,  we  may  eat  garlic 
and  onions  and  not  taste  them.  Hence  the  philosophy  of  hold- 
ing the  nose  when  we  wish  to  swallow  a  nauseous  dose. 

The  sense  of  smell.  —  The  nose  is  the  special  organ  of  the 
sense  of  smell.  It  consists  of  two  parts,  —  the  external  feat- 
ure, the  nose,  and  the  internal  cavities,  the  nasal  fossse.  The 
external  nose  is  composed  of  a  triangular  framework  of  bone 
and  cartilage,  covered  by  skin  and  lined  by  mucous  membrane. 
On  its  under  surface  are  two  oval-shaped  openings  —  the  nos- 
trils—  separated  by  a  partition.  The  margins  of  the  nostrils 
are  provided  with  a  number  of  stiff  hairs  which  arrest  the  pas- 
sage of  dust  and  other  foreign  substances  carried  in  with  the 
inspired  air. 

The  nasal  fossae  are  two  irregularly  wedge-shaped  cavities, 
separated  from  one  another  by  a  partition  or  septum,  and  com- 
municating with  the  air  in  front  by  the  anterior  nares  or  nostrils, 
while  behind  they  open  into  the  back  of  the  pharynx  by  the 
two  posterior  nares.  Fourteen  bones  enter  into  the  formation 


222 


ANATOMY   FOR,  NURSES.          [CHAP.  XIX. 


of  the  nasal  cavities  :  the  floor  is  formed  by  the  palate  and  part 
of  the  superior  maxillary  bones ;  the  roof  is  chiefly  formed  by 
the  perforated  (cribriform)  plate  of  the  ethmoid  bone,  and  by 

the  two  small  nasal  bones ;  and 
in  the  outer  walls  we  find, 
in  addition  to  processes  from 
other  bones,  the  three  scroll- 
like  turbinated  bones.  The 
turbinated  bones,  which  are  ex- 
ceedingly light  and  spongy, 
project  into  the  nasal  cavities, 
and  divide  them  into  three 
incomplete  passages  from  be- 
fore backwards,  —  the  supe- 
rior, middle,  and  inferior  me- 
atus.  The  palate  and  superior 
maxillary  bones  separate  the 
nasal  and  mouth  cavities,  and 
FIG.  129. -VERTICAL  LONGITUDINAL  the  cribriform  plate  of  the  eth- 

SECTION  OF  NASAL  CAVITY.     1,  olfactory  r  .  .         , 

nerve;  v,  branch  of  fifth  nerve;  h,  hard    moid    forms    the    partition    be- 

Palate-  tween  the  cranial  and  nasal 

cavities. 

The  mucous  membrane  (sometimes  called  the  Schneiderian1 
membrane),  which  closely  covers 'the  nasal  passages,  is  thick- 
est and  most  vascular  over  the  turbinated  bones.  In  some 
nasal  troubles  it  becomes  much  thickened  and  swollen  and 
occludes  the  nasal  passages  to  such  an  extent  as  to  compel  us 
to  breathe  through  the  mouth.  It  contains  numerous  mucous 
glands  which  secrete  mucus  for  the  purpose  of  keeping  the 
membrane  moist,  —  a  condition  which  is  essential  to  perfection 
of  the  sense  of  smell. 

The  mucous  membrane  lining  the  nasal  chambers  is  supplied 
with  nerve-fibres  from  the  first  or  olfactory  nerve,  and  also  with 
fibres  of  common  sensation  from  the  fifth  nerve.  The  fibres 
from  the  olfactory  nerves  are  distributed  exclusively  to  the 
upper  air-passages  of  the  nose,  the  mucous  membrane  of  which 
is  covered  with  a  specially  modified  epithelium.  These  fibres 

1  From  Schneider,  the  first  anatomist  who  showed  that  the  secretions  of  the 
nose  proceeded  from  the  mucous  membrane,  and  not,  as  was  formerly  supposed, 
from  the  brain. 


CHAP.  XIX.]      OBGANS  OF   SPECIAL   SENSE.  223 

come  directly  from  the  brain  through  the  cribriform  plate,  and 
are  essential  to  the  sense  of  smell.  Odorous  particles  in  the  air, 
passing  through  the  lower,  wider  air-passages,  pass  by  diffusion 
into  the  higher,  narrower  nasal  chambers,  and,  falling  on  the 
mucous  membrane  provided  with  olfactory  nerve-endings,  pro- 
duce sensory  impulses  which,  ascending  to  the  brain,  give  rise 
to  the  sensations  of  smell. 

If  we  wish  to  smell  anything  particularly  well,  we  sniff  the 
air  up  into  the  higher  nasal  chambers,  and  thus  bring  the  odor- 
ous particles  more  closely  into  contact  with  the  olfactory  nerves. 

Each  substance  we  smell  causes  its  own  particular  sensation, 
and  we  are  not  only  able  to  recognize  a  multitude  of  distinct 
odors,  but  also  to  distinguish  individual  odors  in  a  mixed  smell. 
The  sensation  takes  some  time  to  develop  after  the  contact  of 
the  odorous  stimulus,  and  may  last  a  long  time.  When  the 
stimulus  is  repeated,  the  sensation  very  soon  dies  out,  the 
sensory  terminal  organs  quickly  becoming  exhausted.  Mental 
associations  cluster  more  strongly  round  sensations  of  smell 
than  round  any  other  impressions  we  receive  from  without.  A 
whiff  of  fresh-mown  grass  !  What  associations  will  it  not  con- 
jure up  for  those  happy  mortals  who  spent  their  childish  days 
in  country  lanes  and  fields. 

The  sense  of  hearing.  —  The  ear  is  the  special  organ  of  the 
sense  of  hearing,  and  is  made  up  of  three  portions,  —  the  exter- 
nal ear,  the  middle  ear  or  tympanum,  and  the  internal  ear  or 
labyrinth. 

.  The  external  ear  consists  of  an  expanded  portion,  named 
pinna  or  auricle,  and  the  auditory  canal  or  meatus. 

The  auricle  is  composed  of  a  thin  plate  of  yellow  fibro-car- 
tilage,  covered  with  skin,  and  joined  to  the  surrounding  parts 
by  ligaments  and  a  few  muscular  fibres.  It  is  very  irregular 
in  shape,  and  appears  to  be  an  unnecessary  appendage  to  the 
organ  of  hearing,  except  that  the  central  depression,  the  concha, 
serves  to  some  extent  to  collect  sound-waves,  and  to  conduct 
them  into  the  auditory  canal. 

The  auditory  canal  is  a  tubular  passage,  about  an  inch  and  a 
quarter  in  length,  leading  from  the  concha  to  the  drum-mem- 
brane. It  is  slightly  curved  upon  itself,  so  as  to  be  higher  in 
the  middle  than  at  either  end.  It  is  lined  by  a  prolongation  of 
the  skin,  which  in  the  outer  half  of  the  canal  is  very  thick  and 


224 


ANATOMY  FOR  NURSES.          [CHAP.  XIX. 


not  at  all  sensitive,  and  in  the  inner  half  is  thin  and  highly 
sensitive.  Near  the  orifice  the  skin  is  furnished  with  a  few 
hairs,  and  further  inwards,  with  modified  sweat-glands,  the 
ceruminous  glands,  which  secrete  a  yellow,  pasty  substance, 
resembling  wax. 

The  middle  ear  or  tympanum  is  a  small,  irregularly  flattened 
cavity,  situated  in  the  petrous  portion  of  the  temporal  bone, 
and  lined  with  mucous  membrane.  It  is  separated  from  the 
external  auditory  canal  by  the  drum  membrane  (membrana 


FIG.  130.  —  SEMI-DIAGRAMMATIC  SECTION  THROUGH  THE  RIGHT  EAR.  M,  concha; 
G,  the  external  auditory  canal ;  T,  tympanic,  or  drum-membrane ;  P,  tympanum, 
or  middle  ear;  o,  oval  window;  r,  round  window.  Extending  from  T  too  is  seen 
the  chain  of  the  tympanic  bones;  R,  Eustachian  tube;  V,  B,  S,  bony  labyrinth;  V, 
vestibule;  B,  semicircular  canal;  S,  cochlea;  b,  I,  v,  membranous  labyrinth  in  semi- 
circular canal  and  in  vestibule.  A,  auditory  nerve  dividing  into  branches  for  vesti- 
bule, semicircular  canal  and  cochlea. 

tympani),  and  from  the  internal  ear  by  a  bony  wall  in  which 
there  are  two  small  openings  covered  with  membrane,  —  the 
oval  window  or  fenestra  ovalis,  and  the  round  window  or  fenes- 
tra  rotunda.  The  cavity  of  the  middle  ear  is  so  small  that 
probably  five  or  six  drops  of  water  would  completely  fill  it. 
It  communicates  below  with  the  pharynx  by  the  small  passage 
called  the  Eustachian  tube,  through  which  air  enters  the  cavity 
and  serves  to  keep  the  atmospheric  pressure  equal  on  each 
side  of  the  drum-membrane.  The  middle  ear  also  communi- 
cates above  with  a  number  of  bony  cavities  in  the  mastoid  por- 


CHAP.  XIX.]      ORGANS   OF   SPECIAL   SENSE.  225 

tion  of  the  temporal  bone.1  The  cavities,  called  mastoid  cells, 
are  lined  with  mucous  membrane,  which  is  continuous  with  that 
covering  the"  cavity  of  the  tympanum. 

Stretching  across  the  tympanic  cavity  is  a  chain  of  tiny  mov- 
able bones,  three  in  number,  and  named  from  their  shape 
the  malleus  or  hammer,  the  incus  or  anvil,  and  the  stapes  or 
stirrup.  The  hammer  is  firmly  attached  to  the  drum-mem- 
brane, and  the  stirrup  is  fastened  into  the  oval  window  (also 
covered  by  membrane)  leading  into  the  inner  ear.  The  anvil  is 
placed  between  the  hammer  and  stirrup,  and  attached  to  both 
by  delicate  articulations.  These  little  bones  are  set  in  motion 
with  every  movement  of  the  drum-membrane.  Vibrations  of 
the  membrane  are  communicated  to  the  hammer,  taken  up  by 
the  anvil  and  transmitted  to  the  stirrup,  which  is  driven  slightly 
forward,  and  sets  in  motion  the  membrane  covering  the  oval 
opening  leading  into  the  internal  ear. 

The  internal  ear  or  labyrinth  receives  the  ultimate  termina- 
tions of  the  auditory  nerve,  and  is,  therefore,  the  essential  part 
of  the  organ  of  hearing.  It  consists  of  (1)  a  bony  labyrinth, 
which  is  composed  of  a  series  of  peculiarly  shaped  cavities,  hol- 
lowed out  of  the  petrous  portion  of  the  temporal  bone,  and 
named  from  their  shape  the  vestibule,  the  semicircular  canals, 
and  cochlea  (snail-shell).  This  bony  labyrinth  is  lined  by  a 
serous  membrane,  which  secretes  a  watery  fluid  called  the  peri- 
lymph  ;  and  lying  within  the  bony  labyrinth  and  peri-lymph  is 
(2)  a  membranous  labyrinth,  which  is  composed  of  a  series  of 
sacs  or  tubes,  fitting  more  or  less  closely  within  the  vestibule, 
semicircular  canals,  and  cochlea.  The  membranous  labyrinth 
is  filled  with  a  watery  fluid,  called  the  endo-lymph,  and  is  lined 
for  the  most  part  by  specially  modified  epithelium  cells,  which 
are  connected  with  the  terminations  of  the  auditory  nerve. 

We  may  conceive  of  the  internal  ear  as  a  bony  cavity,  elabo- 
rately tunnelled  from  the  expanded  entrance  or  vestibule  into 
semicircular  canals  above,  and  into  a  canal  resembling  a  snail's 
shell  below.  In  this  bony  labyrinth  is  a  certain  amount  of 
fluid,  and  a  membranous  bag,  drawn  out  and  expanded  at  inter- 
vals to  fit  more  or  less  closely  within  the  bony  labyrinth.  This 
membranous  bag  contains  fluid,  and  is  lined  by  a  most  highly 

1  The  mastoid  portion  of  the  temporal  bone  is  that  rounded  mass  of  bone 
which  one  readily  distinguishes  behind  the  auricle. 


226  ANATOMY   FOK   NUKSES.          [CHAP.  XIX. 

specialized  epithelium,  some  of  the  cells  of  which  have  hair-like 
processes  projecting  into  the  fluid,  others  have  tiny  grains  of 
calcareous  sand 1  attached  to  their  surfaces,  and  all  of  them  are 
connected  with  the  thousands  of  nerve-fibres  into  which  the 
auditory  nerve  divides  after  entering  the  internal  ear.  The 
construction  of  the  whole  ear  and  its  position  in  the  centre  of  a 
bone  is  for  the  purpose  of  protecting  this  delicate  and  highly 
organized  membrane,  by  means  of  which  alone  sound-impres- 
sions can  be  advantageously  conveyed  to  the  brain  and  give  rise 
to  the  sensation  of  hearing. 

All  bodies  which  produce  sound  are  in  a  state  of  vibration 
and  communicate  their  vibrations  to  the  air  with  which  they 
are  in  contact,  and  thus  the  air  is  thrown  into  waves,  just  as  a 
stick  waved  backwards  and  forwards  in  water  throws  the  water 
into  waves. 

When  air-waves,  set  in  motion  by  sonorous  bodies,  enter  the 
external  auditory  canal,  they  set  the  drum-membrane  vibrating, 
stretched  membranes  taking  up  vibrations  from  the  air  with 
great  readiness.  These  vibrations  are  communicated  to  the 
chain  of  tiny  bones  stretching  across  the  middle  ear,  and  their 
oscillations  cause  the  membrane  leading  into  the  internal  ear  to 
be  alternately  pushed  in  and  drawn  out,  and  vibrations  are  in 
this  way  transmitted  to  the  peri-lymph.  Each  vibration  com- 
municated to  the  peri-lymph  travels  as  a  wave  over  the  ves- 
tibule, semicircular  canals,  and  cochlea,  and  is  transmitted 
through  the  membranous  walls  to  the  endo-lymph.  The  vibra- 
tions of  the  endo-lymph  are  communicated  to  the  specially  modi- 
fied cells  connected  with  the  endings  of  the  auditory  nerve,  and 
nervous  impulses  are  conveyed  by  the  auditory  nerve  to  those 
parts  of  the  brain,  stimulation  of  which  gives  rise  to  the  sensa- 
tion of  sound. 

The  effect  produced  by  a  sonorous  vibration  continues  for  a 
short  time  after  the  cessation  of  its  cause.  Usually  the  interval 
between  two  different  impulses  is  sufficient  to  allow  the  first 
impression  to  disappear  before  the  second  is  received,  and  the 
ear  distinguishes  them  in  succession.  But  if  they  follow  each 
other  at  equal  intervals,  with  a  certain  rapidity,  they  produce 

1  In  the  walls  of  the  vestibule  are  two  small  masses,  called  otoliths,  which  are 
composed  of  grains  of  calcareous  sand.  It  is  not  known  what  special  part  these 
otoliths  play  in  the  production  of  sound. 


CHAP.  XIX.]      ORGANS   OF   SPECIAL   SENSE.  227 

the  impression  of  a  continuous  sound ;  and  this  sound  has  a 
higher  or  lower  pitch,  according  to  the  rapidity  of  its  vibra- 
tions. It  has  been  discovered  that  sonorous  impulses  following 
each  other  with  a  rapidity  of  less  than  sixteen  times  per  second, 
are  separately  distinguishable ;  but  above  that  frequency  they 
are  merged  into  a  continuous  sensation.  When  the  sonorous 
impulses  are  repeated  at  irregular  intervals,  the  only  characters 
perceptible  in  the  sound  are  its  intensit}r  and  quality.  But  if 
they  succeed  each  other  at  regular  intervals,  the  sound  pro- 
duced has  a  position  in  the  musical  scale  as  a  high  or  low  note. 
The  more  frequent  the  repetitions,  the  higher  the  note ;  but  a 
limit  is  at  last  reached,  at  which  the  ear  fails  to  perceive  the 
sound,  and  an  excessively  high  note  is  therefore  inaudible. 
Sonorous  vibrations,  perceptible  to  man  as  musical  notes,  range 
between  sixteen  per  second  for  the  lowest  notes,  and  38,000  for 
the  highest.  (Dalton.) 

The  sense  of  sight.  —  The  eye  is  the  special  organ  of  the  sense 
of  sight,  and  consists  of  the  eyeball,  or  eye  proper,  and  of  acces- 
sory protective  appendages,  such  as  the  eyebrows,  eyelids,  lach- 
rymal glands,  etc. 

The  eyeball  is  contained  in  a  bony  cavity,  the  orbit,  which  is 
padded  with  fat  and  lined  with  a  membranous  capsule,  —  the 
capsule  of  Tenon.  This  capsule  is  a  serous  sac,  one  layer  of 
which  is  attached  to  the  posterior  portion  of  the  eyeball,  while 
the  other  lines  the  orbital  cavity:  in  this  way  the  eyeball  is 
isolated  from  surrounding  structures,  and  free  movement  with- 
out friction  is  insured.  The  orbit  is  shaped  like  a  four-sided 
pyramid ;  the  apex,  directed  backwards  and  inwards,  is  pierced 
by  a  large  opening,  —  the  optic  foramen,  —  through  which  pass 
the  nerves  and  blood-vessels  distributed  to  the  eyeball.  The 
base  of  the  orbit,  directed  outwards  and  forwards,  forms  a  strong 
bony  edge  for  protecting  the  eyeball  from  injury. 

The  eyeball  is  spherical  in  shape,  but  its  transverse  diameter 
is  less  than  the  antero-posterior,  so  that  it  projects  anteriorly, 
and  looks  as  if  a  section  of  a  smaller  sphere  had  been  engrafted 
on  the  front  of  it. 

The  eyeball  is  composed  of  three  coats  or  tunics,  and  contains 
three  refracting  media  or  humours.  They  are  as  follows :  — 

Tunics.  —  1.  Sclerotic  and  cornea. 

2.  Choroid,  iris,  and  ciliary  processes. 

3.  Retina. 


228  ANATOMY  FOR  NUKSES.          [CHAP.  XIX. 

Befr acting  media.  —  1.  Aqueous. 

2.  Crystalline  lens  and  capsule. 

3.  Vitreous. 

The  sclerotic  (derived  from  a  Greek  word  signifying  hard) 
covers  the  posterior  five-sixths  of  the  eyeball.  It  is  composed 
of  a  firm,  unyielding,  fibrous  membrane,  thicker  behind  than  in 
front,  and  serves  to  protect  the  delicate  structures  contained 


FIG.  131. — THE  LEFT  EYEBALL  IN  HORIZONTAL  SECTION  FROM  BEFORE  BACK. 
1,  sclerotic;  2,  junction  of  sclerotic  and  cornea;  3,  cornea;  4,  5,  conjunctival  mem- 
brane ;  7,  ciliary  muscle ;  10,  choroid ;  11,  13,  ciliary  processes ;  14,  iris ;  15,  retina ; 
16,  optic  nerve;  17,  artery  entering  retina;  18,  fovea  centralis;  19,  region  where 
sensory  part  of  retina  ends ;  26,  27,  28,  are  placed  on  the  lens ;  28,  suspensory  liga- 
ment placed  around  lens;  29,  vitreous  humour ;  30,  aqueous  humour  in  anterior 
chamber. 


within  it.  It  is  opaque,  white  and  smooth  externally,  and 
behind  is  pierced  by  the  optic  nerve.  Internally  it  is  stained 
brown  where  it  comes  in  contact  with  the  choroid  coat.  The 
cornea  (derived  from  Latin  cornu,  horn,  and  therefore  also  sig- 
nifying hard)  covers  the  anterior  sixth  of  the  eyeball.  It  is 
directly  continuous  with  the  sclerotic  coat,  which,  however, 
overlaps  it  slightly  above  and  below,  as  a  watch-crystal  is  over- 
lapped by  the  case  into  which  it  is  fitted.  The  cornea,  like  the 


CHAP.  XIX.]      OKGANS   OF   SPECIAL    SENSE.  229 

sclerotic,  is  composed  of  fibrous  tissue,  which  is  both  firm  and 
unyielding,  but,  unlike  the  sclerotic,  it  has  no  colour,  and  is 
perfectly  transparent:  it  has  been  aptly  termed  the  "window 
of  the  eye."  Both  the  cornea  and  the  anterior  portion  of  the 
sclerotic  are  covered  by  reflections  of  the  mucous  membrane 
lining  the  eyelids.  This  is  called  the  conjunctiva,  and,  kept 
well  lubricated  by  the  secretions  of  the  eye,  gives  the  eyeball 
its  peculiar  shining  and  glossy  aspect.  The  sclerotic  is  supplied 
with  very  few  blood-vessels,  and  the  existence  of  nerves  in  it  is 
doubtful ;  while  the  cornea  has  no  blood-vessels,  but  is  well 
supplied  with  nerves. 

The  choroid,  or  vascular  coat  of  the  eye,  is  a  thin  dark-brown 
membrane  lining  the  inner  surface  of  the  sclerotic.  It  is  com- 
posed of  connective  tissue,  the  cells  of  which  are  large  and 
filled  with  pigment,  and  it  contains  a  close  network  of  blood- 
vessels. It  extends  to  within  a  short  distance  of  the  cornea, 
and  then  is  folded  inwards  and  arranged  in  radiating  folds,  like 
a  plaited  ruffle,  around  the  lens  and  just  behind  the  edge  of 
the  cornea.  The  choroid  coat,  properly  speaking,  terminates 
anteriorly  in  the  ciliary  processes,  arranged,  as  above  stated,  in 
a  radiating  circle  round  the  lens ;  but  closely  connected  with 
the  anterior  margin  of  the  choroid  is  the  iris. 

The  iris  (iris,  rainbow)  is  a  coloured,  fibre-muscular  curtain 
hanging  in  front  of  the  lens  and  behind  the  cornea.  It  is 
attached  at  its  circumference  to  the  choroid,  with  which  it  is 
practically  continuous,  and  is  also  connected  to  the  sclerotic 
and  cornea  at  the  point  where  they  join  one  another.  Except 
for  this  attachment  at  its  circumference,  it  hangs  free  in  the 
interior  of  the  eyeball.  In  the  middle  of  the  iris  is  a  circular 
hole  —  the  pupil — through  which  light  is  admitted  into  the 
eye-chamber.  The  iris,  like  the  choroid,  is  composed  of  con- 
nective tissue  containing  a  large  number  of  pigment  cells  and 
numerous  blood-vessels.  It  contains  in  addition  two  sets  of 
plain  muscular  fibres.  One  set  forms  a  flat  band  round  the 
margin  of  the  pupil,  and  is  called  the  sphincter  or  contractor 
of  the  pupil ;  the  other  set  consists  of  radiating  fibres  converg- 
ing from  the  circumference  to  the  centre,  and  is  called  the 
dilator  of  the  pupil.  The  action  of  these  muscle-fibres  is 
affected  by  light.  Under  the  influence  of  a  bright  light  the 
pupil  involuntarily  contracts  so  that  less  light  is  admitted  into 


230 


ANATOMY   FOR   NURSES.  [CHAP.  XIX. 


the  eye-chamber;  in  a  dim  light  the  pupil  involuntarily  dilates 
to  admit  as  much  light  as  possible.  The  posterior  surface  of 
the  iris  is  covered  by  a  thick  layer  of  pigment-cells  designed 
to  darken  the  curtain  and  prevent  the  entrance  of  light.  The 

anterior  surface  of  the  iris 
is  also  covered  with  pig- 
ment cells,  and  it  is  chiefly 
these  latter  which  cause  the 
beautiful  colours  seen  in  the 
iris.  The  different  colours 
of  eyes,  however,  are  mainly 
due  to  the  amount,  and  not 
to  the  colour,  of  the  pig- 
ment deposited. 

The  retina,  the  innermost 
coat  of  the  eyeball,  is  the 
most  essential  part  of  the 
organ  of  sight,  since  it  is 
the  only  one  directly  sensi- 
tive to  light.  The  sclerotic 
is  the  protective,  the  choroid 
the  vascular  or  nutritive, 
and  the  retina  is  the  visual 
or  perceptive,  layer  of  the 
eyeball.  It  forms  a  nearly 
transparent  membrane  situ- 
ated between  the  inner  sur- 
face of  the  choroid  and  the 
outer  surface  of  the  vitre- 
ous humour,  and  extending 

FIG   132. -DIAGRAMMATIC     SECTION     OF  from    the    entrance     of    the 
THE  HUMAN    KETINA.     (M.    Schultze.)      a, 

inner    surface;    b,  internal    limiting    mem-  OptlC     nerve     to      the     COm- 

brane;   1,  layer  of  nerve-fibres;    2,  layer  of  mencement     of     the     ciliary 

processes,  where  it  termi- 
nates by  an  indented  border, 
the  ora  serrata.  It  is  composed  of  eight  layers  and  two  limiting 
membranes,  as  shown  in  the  accompanying  figure  (Fig.  132). 
The  most  essential  of  these  layers  are  the  first  and  second,  — 
the  layer  of  nerve-fibres  and  the  layer  of  nerve-cells,  —  and  the 
seventh  layer,  —  the  layer  of  the  rods  and  cones.  The  layer  of 


nerve-cells ;  c,  external  limiting  membrane ; 
7,  layer  of  rods  and  cones ;  8,  pigment  cells ; 
d,  outer  surface. 


CHAP.  XIX.]       ORGANS   OF   SPECIAL   SENSE.  231 

nerve-fibres  is  formed  by  the  expansion  of  the  optic  nerve  after 
it  has  passed  through  the  sclerotic  and  choroid  coats  at  the  back 
of  the  eye.  At  its  entrance  it  forms  a  slight  prominence,  and 
then  radiates  latterly  in  every  direction  in  the  form  of  a  closely 
set  layer  of  fine  fibrils.  The  second  layer,  or  layer  of  nerve- 
cells,  consists  for  the  most  part  of  bipolar l  cells,  processes  from 
which  extend  into  the  layer  above  and  below. 

The  layer  of  rods  and  cones  is  the  most  remarkable  of  all  the 
retinal  layers;  it  is  composed  of  elongated  nucleated  cells, 
which  are  supposed  by  some  authorities  to  be  highly  specialized 
epithelium  cells :  they  are  directly  concerned  in  producing  the 
sensation  of  light.  Rays  of  light  produce  no  effect  upon  the 
optic  nerve  without  the  intervention  of  the  rods  and  cones. 
This  is  proved  by  the  fact  that  at  the  entrance  of  the  optic 
nerve  there  are  no  rods  and  cones,  and  this  spot  is  quite  blind, 
rays  of  light  falling  upon  it  producing  no  sensation.  There  is 
one  point  of  the  retina  which  is  of  great  importance,  and  that  is 
the  macula  lutea,  or  yellow  spot.  It  is  situated  about  j1^-  of  an 
inch  to  the  outer  side  of  the  entrance  of  the  optic  nerve.  In  its 
centre  is  a  tiny  pit  (fovea  centralis)  which  is  the  centre  of 
direct  vision ;  that  is,  it  is  the  part  of  the  retina  which  is  always 
turned  towards  the  object  looked  at.  From  this  point  the  sen- 
sitiveness of  the  retina  grows  less  and  less  in  all  directions.  In 
the  fovea  centralis  the  rods  are  highly  developed,  but  most  of 
the  other  layers  of  the  retina  are  wanting. 

Light  may  be  described  as  consisting  of  vibrations  in  the  ether 
which  pervades  space.  These  ethereal  vibrations  enter  the  eye 
through  the  cornea,  pass  on  through  the  pupil  and  refracting 
media,  and  strike  on  the  retina.  Here  they  excite  the  rods  and 
cones  (cell-bodies  specially  adapted  for  receiving  stimulation 
from  rays  of  light),  and  these  pass  on  their  stimulation  to  the 
fibres  of  the  optic  nerve,  which  in  turn  transmit  the  stimulus  to 
the  visual  centre  in  the  brain,  and  the  sensation  and  perception 
of  light  is  produced. 

Behind  the  layer  of  rods  and  cones,  and  lying  on  the  choroid, 
is  a  beautiful  mosaic  layer  of  pigment  cells  containing  a  purple 
substance  which  stains  the  rods,  and  is  constantly  bleached  by 
the  action  of  light  and  regenerated  in  the  dark. 

The  refracting  media  of  the  eye.  —  The  interior  of  the  eyeball 

1  A  bipolar  cell  is  a  cell  having  two  processes. 


232  ANATOMY   FOE   NUESES.  [CHAP.  XIX. 

is  divided  into  two  chambers  by  the  crystalline  lens  and  iris. 
The  "  anterior  chamber,"  the  portion  in  front  of  the  iris,  is  rilled 
with  a  colourless,  transparent  watery  fluid,  the  aqueous  humour. 
The  "posterior  chamber"  is  filled  with  a  semi-fluid  gelatinous 
substance,  the  vitreous  humour  or  body,  so  called  from  its  glassy 
and  transparent  appearance.  Its  refractive  power,  though 
slightly  greater  than  that  of  the  aqueous  humour,  does  not  differ 
much  from  that  of  water.  It  distends  the  greater  part  of  the 
sclerotic,  supports  the  retina,  which  lies  upon  its  surface,  and 
preserves  the  spheroidal  shape  of  the  eyeball. 

The  crystalline  lens  is  a  transparent  refractive  body,  with  con- 
vex anterior  and  posterior  surfaces,  placed  directly  behind  the 
pupil,  where  it  is  retained  in  position  by  the  counterbalancing 
pressure  of  the  aqueous  humour  and  vitreous  body,  and  by  its 
own  suspensory  ligament.  It  is  a  fibrous  body,  composed  of 
long  riband-shaped  fibres  and  enclosed  in  an  elastic  capsule. 
Its  refractive  power  is  greater  than  that  of  the  aqueous  or 
vitreous  humour,  and  it  acts  by  virtue  of  its  double-convex 
form  as  a  converging  lens,  bringing  parallel  or  diverging  rays 
to  a  focus  on  the  posterior  surface  of  the  retina.  The  function 
of  the  crystalline  lens  is  to  give  perception  of  form  and  outline. 
If  the  eye  consisted  only  of  a  sensitive  retina,  impressions  of 
light  could  be  received,  but  the  form  of  objects  would  not  be 
distinguished.  By  focussing  the  rays  emanating  from  an  ex- 
ternal object,  the  crystalline  lens  produces  a  distinct  inverted 
image  of  the  object  on  the  retina. 

The  action  of  the  lens,  in  thus  focussing  the  rays  of  light  at 
a  particular  point,  may  be  illustrated  in  the  following  manner : 
If  a  sheet  of  white  paper  be  held  at  a  short  distance  from  a 
candle-flame,  in  a  room  with  no  other  light,  the  whole  of  the 
paper  will  be  moderately  and  uniformly  illuminated  by  the 
diverging  rays.  But  if  a  double-convex  lens,  with  suitable  cur- 
vatures, be  interposed  between  the  paper  and  the  light,  the 
outer  portions  of  the  paper  will  become  darker,  and  its  central 
portion  brighter,  because  a  portion  of  the  rays  are  diverted 
from  their  original  course  and  bent  inward.  By  varying  the 
distance  of  the  lens  from  the  paper,  a  point  will  at  last  be 
found  where  none  of  the  light  reaches  the  external  parts  of  the 
sheet,  but  all  of  it  is  concentrated  upon  a  single  spot ;  and  at 
this  spot  will  be  seen  a  distinct  image  of  the  candle  and  its 
flame. 


CHAP.  XIX.]       ORGANS   OF   SPECIAL   SENSE.  233 

Perception  of  the  figure  of  external  objects  therefore  depends 
on  the  action  of  the  crystalline  lens  in  converging  all  the  rays, 
emanating  from  a  given  point,  to  a  focus  on  the  retina.  When 
the  lens  of  the  eye  is  too  convex,  and  its  refractive  power 
excessive,  the  rays  of  light  converge  too  soon  and  cross  one 
another  before  reaching  the  retina ;  consequently,  the  image 
produced  is  not  concentrated  and  distinct,  but,  dispersed  more 
or  less  over  the  surface  of  the  retina,  is  diffused  and  dim.  On 
the  other  hand,  if  the  lens 
is  too  flat,  the  rays  do  not 
converge  soon  enough,  and 
the  image  is  again  diffused 
and  indistinct.  To  remedy 
a  too  great  convexity  of  the 
lens  in  the  short-sighted  or 
myopic  eye,  concave  specta- 
cles are  used  to  disperse  the 
rays ;  to  remedy  the  flattened 
lens  in  the  hypermetropic  or 
long-sighted  eye,  we  employ 
convex  glasses  to  concen- 
trate and  focus  the  rays 
more  quickly. 

A  normal  eye  is  capable 

of    distinct    vision    through-       FlG    133  _  DlAGBAM  ILLUSTRATING  RAYS 

OUt  an  immense  range.     We    OF  LIGHT  CONVERGING  IN  A  NORMAL  EYE, 

.7,.  „    (A),  A  MYOPIC   EYE,    (B),  AND  A  HYPER- 

can  see  the  stars  millions  ot  METROPIC  EYE  (C). 
miles    away,   and  with   the 

same  eye,  though  not  at  the  same  time,  we  can  see  objects  within 
a  few  inches  of  us.  To  be  able  to  see  objects  millions  of 
miles  away  and  within  a  short  range,  the  eye  has  to  accom- 
modate or  adjust  itself  to  different  distances.  This  ac- 
commodation is  accomplished  mainly  by  the  lens  changing  its 
convexity.  In  accommodation  for  near  objects,  the  lens  becomes 
more  convex  and  the  pupil  of  the  eye  likewise  contracts.  This 
convexity  is  brought  about  by  muscular  effort,1  and  is  always 
more  or  less  fatiguing.  The  accommodation  for  distant  objects 
is  a  passive  condition,  the  convexity  of  the  lens  being  unaltered 

1  Connected  with  the  lens  are  tiny  muscles,  —  the  ciliary  muscles,  —  contraction 
of  which  alters  the  shape  of  the  lens. 


234  ANATOMY   FOE,  NUESES.  [CHAP.  XIX. 

and  the  pupil  of  the  eye  dilated,  and  it  is  on  this  account  that 
the  eye  rests  for  an  indefinite  time  upon  remote  objects  without 
fatigue. 

The  eyeball  is  often  compared  to  a  photographer's  camera. 
It  is  essentially  a  hollow  spherical  box  filled  with  fluids,  having 
its  interior  surface  blackened  by  pigment,  and  containing  a 
system  of  lenses  by  means  of  which  images  can  be  formed,  and 
a  screen  upon  which  they  can  be  received.  In  front  is  a  cur- 
tain or  diaphragm  (the  iris),  with  a  variable  central  aperture 
(the  pupil)  to  regulate  the  amount  of  light  admitted. 

The  colour  of  light  is  considered  to  be  analogous  to  the  pitch 
of  sound.  As  the  latter  is  determined  by  the  number  of  vibra- 
tions of  the  atmosphere  which  strike  the  ear  in  a  second,  so  the 
former  depends  on  the  waves  of  ether  which  strike  the  retina  in 
a  second.  The  lowest  note  of  an  ordinary  musical  scale  has, 
as  we  have  already  remarked,  sixteen  vibrations  per  second; 
the  highest,  38,000  per  second.  The  number  of  ether-waves 
which  strike  the  retina  in  a  second  to  produce  the  sensation  of 
red  (which  lies  at  the  bottom,  so  to  speak,  of  the  colour-scale) 
is  estimated  at  474,439,680,000,000.  The  number  required  to 
cause  the  sensation  of  violet,  which  lies  at  the  other  extreme  of 
our  colour-perception,  is  estimated  at  699,000,000,000,000  ! 

The  muscles  which  move  the  eyeball  are  the  four  straight  or 
recti  and  the  two  oblique.  They  have  been  sufficiently  de- 
scribed on  page  58. 

The  appendages  of  the  eye  are  the  eyebrows,  eyelids  and 
lachrymal  glands. 

The  eyebrows  are  composed  of  two  arched  eminences  of 
thickened  skin,  connected  with  three  muscles,  which  by  their 
action  control  to  a  limited  extent  the  amount  of  light  admitted 
into  the  eye.  The  eyebrows  are  furnished  with  numerous 
short,  thick  hairs,  lying  obliquely  on  the  surface. 

The  eyelids  are  two  folds,  projecting  from  above  and  below 
in  front  of  the  eye.  They  are  covered  externally  by  the  skin 
and  internally  by  a  mucous  membrane,  the  conjunctiva,  which 
is  reflected  from  them  over  the  globe  of  the  eye.  They  are 
composed  for  the  most  part  of  connective  tissue,  which  is 
dense  and  fibrous  under  the  conjunctiva,  where  it  is  known 
as  the  tarsus. 

Embedded  in  the  tarsus  is  a  row  of  elongated  sebaceous  glands 


CHAP.  XIX.]        ORGANS   OF   SPECIAL  SENSE. 


235 


(the  Meibomian  glands *),  the  ducts  of  which  open  on  the  edge 
of  the  eyelid.  The  secretion  of  these  glands  is  provided  to 
prevent  adhesion  of  the  eyelids. 

Arranged  in  a  double  or  triple  row  at  the  margin  of  the  lids 
are  the  eyelashes ;  those  of  the  upper  lid,  more  numerous  and 
longer  than  the  lower,  curve  upwards ;  those  of  the  lower  lid 
curve  downwards,  so  that  they  do  not  interlace  in  closing  the 
lids.  The  upper  lid  is  attached  to  a  small  muscle  which  is 
called  the  elevator  of  the  upper  lid;  and  arranged  as  a  sphincter 
around  both  lids  is  the  orbicularis  palpelrarum  muscle,  which 
closes  the  eyelids,  and  is  the  direct  antagonist  of  the  elevator  of 
the  upper  lid. 

The  slit  between  the  edges  of  the  lids  is  called  the  palpe- 
bral  fissure.  It  is  the  size  of  this  fissure  which  causes  the 
appearance  of  large  and  small  eyes,  as  the  size  of  the 
lobe  itself  varies  but  little.  The  outer  angle  of  this  fissure  is 
called  the  external  canthus  ;  the  inner  angle,  the  internal  can- 
thus. 

The  eyelids  are  obviously  provided  for  the  protection  of  the 
eye  ;  movable  shades  which  by  their  closure  exclude  light,  par- 
ticles of  dust,  and  other 
injurious  substances. 

The  lachrymal  gland  is 
a  compound  gland,  closely 
resembling  the  salivary 
glands  in  structure.  It 
secretes  the  tears,  and  is 
lodged  in  a  depression  at 
the  outer  angle  of  the 
orbit.  It  is  about  the  size 
and  shape  of  an  almond. 
Its  ducts  run  obliquely 
beneath  the  conjunctiva, 
and  open  by  a  series  of 
minute  orifices  upon  the 
upper  surface  of  the  eye. 

After  passing  over  the  surface  of  the  eyeball,  the  tears  are  carried 
away  through  minute  openings  in  the  inner  angle  of  the  eye  into 

1  By  inverting  the  eyelids,  these  glands  may  be  seen  through  the  conjunctiva 
lying  in  parallel  rows. 


FIG.  134. — THE  LACHRYMAL  APPARATUS. 


236  ANATOMY   FOR   NURSES.  [CHAP.  XIX 

the  lachrymal  sac,  which  is  the  upper  dilated  portion  of  the  nasal 
duct. 

The  nasal  duct  is  a  membranous  canal,  about  three-quarters 
of  an  inch  in  length,  which  extends  from  the  lachrymal  sac  to 
the  inferior  meatus  of  the  nose,  into  which  it  opens  by  a  slightly 
expanded  orifice. 

The  tears  consist  of  water  containing  a  little  salt  and  albu- 
min. They  are  ordinarily  carried  away  as  fast  as  formed,  but 
under  certain  circumstances,  as  when  the  conjunctiva  is  irri- 
tated, or  when  painful  emotions  arise  in  the  mind,  the  secretion 
of  the  lachrymal  gland  exceeds  the  drainage  power  of  the  nasal 
duct,  and  the  fluid,  accumulating  between  the  lids,  at  length 
overflows,  and  runs  down  the  cheeks. 


CHAPTER  XX. 

FEMALE  GENERATIVE  ORGANS. 

THE  internal  female  generative  organs  are  vagina,  uterus, 
Fallopian  tubes,  and  ovaries. 

The  vagina.  —  The  vagina  is  a  distensible  and  curved  musculo- 
membranous  canal,  extending  from  the  vulva  to  the  uterus. 
The  posterior  wall  is  about  three  and  a  half  inches  long,  while 
the  anterior  wall  is  only  three  inches.  The  front  or  anterior 
wall  is  united  by  connective  tissue  with  the  posterior  walls  of 
the  bladder  and  urethra,  the  partition  or  septum  between  the 
bladder  and  vagina  being  called  the  vesico-vaginal,  and  that 
between  the  urethra  and  vagina,  the  urethro-vaginal,  septum. 
And,  if  we  divide  the  posterior  wall  of  the  vagina  into  five 
sections,  we  find  that  the  middle  three-fifths  is  connected  with 
the  rectum,  the  united  walls  forming  the  recto-vaginal  septum;1 
the  lower  fifth  is  separated  from  the  rectum  and  is  joined  to  the 
perineum;2  while  the  upper  fifth  extends  up  behind  the  neck  of 
the  uterus. 

The  vagina  is  made  up  of  three  coats,  an  outer,  fibrous; 
middle,  muscular ;  and  inner,  mucous.  The  muscular  coat  in- 
creases during  pregnancy, 'and  the  mucous  coat  is  arranged  in 
transverse  folds  or  rugae,  which  allow  of  dilatation  of  the  canal 
during  labour. 

The  uterus.  —  The  uterus  is  a  thick -walled,  hollow,  pear- 
shaped  organ,  situated  in  the  middle  of  the  pelvic  cavity.  Its 
upper  end  is  a  little  below  the  level  of  the  superior  strait  of  the 
pelvis  (vide  page  43) ;  its  lower  end  projects  into  the  vagina. 

1  Perforations  of  the  vesico-vaginal  and  recto-vaginal  partitions  constitute 
vesico-vaginal  and  recto-vaginal  fistulae. 

2  The  perineum  is  a  triangular  section  of  tissue,  made  up  of  muscles  strength- 
ened with  fascia,  placed  between  the  rectum  and  vagina,  and  forming  the  floor 
of  the  pelvis. 

237 


238  ANATOMY   FOR  NURSES.  [CHAP.  XX. 

The  bladder  lies  in  front  of  it ;  the  rectum,  behind ;  the  vagina, 
below;  and  the  small  intestine  rests  upon  it  above.  Its  length 
is  roughly  estimated  to  be  about  three  inches;  its  greatest 
width,  one  and  one-half  inches;  and  its  thickness,  one  inch. 
At  the  end  of  pregnancy  it  attains  the  length  of  a  foot  or  more, 
and  measures  about  eight  to  ten  inches  transversely. 

The  uterus  is  divided  for  purposes  of  description  into  three 


FIG.  135.  —  SECTION  OF  FEMALE  PELVIS,  SHOWING  RELATIVE  POSITION  OF  VISCERA. 

parts,  the  fundus,  body,  and  neck.  The  fundus  is  the  rounded 
portion  projecting  above  a  line  drawn  transversely  through  the 
upper  part  of  the  organ.  The  body  is  the  portion  extending 
from  the  rounded  section,  the  fundus,  to  the  constricted  section, 
the  neck.  The  neck  or  cervix  extends  from  the  body  of  the 
uterus  into  the  vagina. 

Owing  to  the  thickness  of  its  walls,  the  cavity  of  the  uterus 


CHAP.  XX.]       FEMALE   GENERATIVE   ORGANS.  239 


is  comparatively  small.  The  cavity  is  triangular  in  shape 
and  has  three  openings,  one  at  each  upper  angle,  communicating 
with  the  Fallopian  tubes,  and  one,  the  os  internum,  or  internal 
mouth,  opening  into  the  cavity  of  the  cervix  below.  The 
cavity  of  the  cervix,  which  is,  of  course,  continuous  with  the 
cavity  in  the  body,  is  constricted  above,  where  it  opens  into 
the  body  by  means  of  the  os  internum,  and  below,  where  it 
opens  exteriorly  by  means  of  the  os  extern  um,1  or  external 
mouth.  Between  these  two  openings,  the  cavity  of  the  cervix 
is  somewhat  enlarged. 

The  walls  of  the  uterus  consist  mainly  of  bundles  of  plain 
muscular  tissue,  arranged  in  layers  which  run  circularly,  longi- 
tudinally, spirally,  and  cross  and  interlace  in  every  direction. 
A  part  of  the  external  surface  is  covered  by  a  portion  of  the 
peritoneum  in  the  form  of  a  broad  ligament,  and  the  inner  sur- 
face is  lined  by  a  mucous  membrane.  This  mucous  membrane 
is  continuous  with  that  lining  the  vagina  and  Fallopian  tubes. 
It  is  highly  vascular,  provided  with  numerous  mucous  glands, 
and  is  covered  with  ciliated  epithelium. 

The  uterus  is  abundantly  supplied  with  blood-vessels,  lym- 
phatics, and  nerves.  The  blood  reaches  the  uterus  by  means  of 
the  uterine  arteries  from  the  internal  iliacs,  and  the  ovarian 
arteries  from  the  aorta.  Where  the  neck  joins  the  body  of  the 
uterus,  the  arteries  from  both  sides  are  united  by  a  branch 
vessel,  called  the  circumflex  artery.  If  this  branch  is  cut  dur- 
ing a  surgical  operation,  or  a  tear  of  the  neck  during  parturi- 
tion extends  so  far  as  to  sever  it,  the  hemorrhage  is  very 
profuse.  The  arteries  are  remarkable  for  their  tortuous  course 
and  frequent  anastomoses.  The  veins  are  of  large  size  and  cor- 
respond in  their  behaviour  to  the  arteries. 

During  pregnancy  all  the  tissues  of  the  uterus  become  much 
enlarged,  undergoing  what  is  called  a  physiological  hypertrophy. 
The  uterus  increases  in  weight  from  two  or  three  ounces  to  two 
or  three  pounds.  After  parturition,  it  goes  back  to  nearly  its 
former  size.  The  tissues  all  go  through  a  gradual  shrinkage,  or 
what  is  called  a  physiological  atrophy.  The  enlarged  muscles 
especially  undergo  fatty  degeneration  and  absorption,  called 
"involution,"  in  contradistinction  to  "evolution"  or  develop- 

1  The  os  externum  is  bounded  by  two  folds  or  lips  of  the  mucous  membrane, 
the  anterior  of  which  is  thick,  and  the  posterior  narrow  and  long. 


240  ANATOMY   FOR  NUKSES.  [CHAP.  XX. 

me  lit.  This  process  of  involution  is  not  accomplished  under 
six  weeks,  and  sometimes  requires  longer. 

The  uterus  is  not  firmly  attached  or  adherent  to  any  part  of 
the  skeleton.  It  is,  as  it  were,  suspended  in  the  pelvic  cavity, 
and  kept  in  position  by  ligaments.  A  full  bladder  pushes  it 
backward ;  a  distended  rectum,  forward.  It  alters  its  position, 
by  gravity,  with  change  of  posture.  During  gestation  it  rises 
into  the  abdominal  cavity. 

The  uterus  has  five  pairs  of  ligaments  attached  to  it,  the 
chief  of  which  are  the  broad  and  round  ligaments.  The  broad 
ligaments  are  folds  of  peritoneum  slung  over  the  front  and  back 
of  the  uterus,  and  extending  laterally  to  the  walls  of  the  pelvis. 
The  anterior  fold  covers  the  front  of  the  uterus  as  far  as  the 
middle  of  the  cervix,  when  it  turns  up  and  is  reflected  over 


^risOe  patted  thrva& 


FIG.  136.— THE  UTERUS  AND  ITS  APPENDAGES.    ANTERIOR  VIEW. 

the  back  wall  of  the  bladder.  The  posterior  fold  covers  the 
back  of  the  uterus,  and  extends  far  enough  below  to  also 
cover  the  upper  one-fifth  of  the  back  wall  of  the  vagina,  when 
it  turns  up  and  is  reflected  over  the  anterior  wall  of  the  rectum. 
Thus  the  uterus,  with,  and  between  its  two  broad  ligaments, 
forms  a  transverse  partition  in  the  pelvic  cavity,  the  bladder, 
vagina,  and  urethra  being  in  the  front  compartment,  and  the 
rectum  in  the  back  compartment.  The  round  ligaments  are  two 
rounded  nbro-muscular  cords,  situated  between  the  folds  of  the 
broad  ligament.  They  are  about  four  and  a  half  inches  long, 
and  extend  from  the  upper  angle  of  the  uterus  forwards  and 
outwards  to  be  inserted  into  the  vulva. 

Fallopian  tubes.  —  The  Fallopian 1  tubes  or  oviducts  are  pro- 
1  Named  after  Fallopius,  an  Italian  anatomist. 


CHAP.  XX.]       FEMALE   GENERATIVE   OKGANS.  241 

vided  for  the  purpose  of  conveying  the  ova  from  the  ovaries 
into  the  cavity  of  the  uterus.  They  are  two  in  number,  one  on 
each  side,  and  pass  from  the  upper  angles  of  the  uterus  in  a 
somewhat  tortuous  course  between  the  folds  and  along  the 
upper  margin  of  the  broad  ligament,  towards  the  sides  of  the 
pelvis.  Each  tube  is  about  four  inches  in  length.  Its  canal  is 
exceedingly  small,  and  begins  at  the  upper  angle  of  the  uterus 
by  a  minute  opening  which  will  hardly  admit  of  a  fine  bristle. 
It  continues  narrow  along  the  inner  half  of  the  tube,  and  then 
gradually  widens  into  a  trumpet-shaped  extremity,  which  be- 
comes contracted  at  its  termination.  The  margins  of  the  free 
trumpet-shaped  extremity  are  frayed  out  into  a  number  of 
fringe-like  processes,  called  fimbrice  and  one  of  these  processes, 
longer  than  the  rest,  is  connected  with  the  outer  end  of  the 
ovary. 

The  Fallopian  tube  consists,  like  the  uterus,  of  three  coats : 
the  external  or  serous  coat,  derived  from  the  peritoneum ;  the 
middle  or  muscular  coat,  having  a  layer  of  longitudinal  and  of 
circular  fibres  ;  and  the  internal  or  mucous  coat,  continuous  at 
the  inner  end  with  the  mucous  lining  of  the  uterus,  and  at  the 
distal  end  with  the  serous  lining  of  the  abdominal  cavity.  This 
is  the  only  instance  in  the  body  in  which  a  mucous  and  serous 
lining  are  continuous  with  one  another. 

When  the  ovum  is  ready  for  entrance  into  the  Fallopian 
tube,  the  fimbrise  of  the  free  end  grasp  the  ovary,  the  tiny 
germ-cell  is  safely  conducted  into  the  trumpet-shaped  ex- 
tremity, and  is  thence  carried  along  by  the  peristaltic  motion 
of  the  oviduct  into  the  uterus.  This  transmission  of  the  cell  is 
also  assisted  by  the  ciliated  epithelium  lining  the  tube,  the 
motion  of  the  cilia  wafting  it  onwards. 

The  ovaries.  —  The  ovaries  are  two  small  almond-shaped 
bodies*  situated  one  on  each  side  of  the  uterus,  between  the 
anterior  and  posterior  folds  of  the  broad  ligament,  and  below 
the  Fallopian  tubes.  Each  ovary  is  attached  by  its  inner  end 
to  the  uterus  by  a  short  ligament  —  the  ligament  of  the  ovary ; 
and  by  its  outer  end  to  the  Fallopian  tube  by  one  of  the  fringe- 
like  processes  of  the  fimbriated  extremity.  The  ovaries  each 
measure  about  one  and  a  half  inches  in  length,  three-fourths  of 
an  inch  wide,  and  one-third  of  an  inch  thick,  and  weigh  from 
one  to  two  drachms.  Their  function  is  to  produce,  develop, 


242 


ANATOMY  FOR  NURSES.  [CHAP.  XX. 


and  mature  the  ova,  and  to  discharge  them  when  fully  formed 
from  the  ovary. 

The  ovaries  consist  of  a  framework  of  connective  and  muscu- 
lar tissue,  usually  called  the  stroma  or  bed  of  the  organ  ;  and  of 


FIG.  137.  — SECTION  OF  AN  OVARY.  (Waldeyer.)  a,,  germ-epithelium ;  6,  egg- 
tubes  ;  c,  c,  small  follicles ;  d,  more  advanced  follicle ;  e,  discus  proligerus  and  ovum ; 
/,  second  ovum  in  same  follicle  (this  occurs  but  rarely) ;  g,  outer  tunic  of  the  follicle ; 
h,  inner  tunic;  i,  membrana  granulosa;  k,  collapsed  retrograded  follicle;  I,  I,  blood- 
vessels; y,  involuted  portion  of  the  germ-epithelium  of  the  surface;  z,  place  of  the 
transition  from  peritoneal  to  germinal  or  ovarian  epithelium. 

numerous    vesicles   or   follicles   of    different   sizes,    called   the 
Graafian  follicles. 

The  stroma  contains  many  blood-vessels  and  lymphatics.     The 
outer  portion  is  more  condensed  than  the  interior,  and  the  whole 


CHAP.  XX.]     FEMALE   GENERATIVE   ORGANS.  243 

is  covered  by  a  peculiar  layer  of  columnar  epithelium-cells, 
called  germinal  epithelium. 

The  Graafian  follicles  are  cavities  dotted  about  in  the  stroma 
in  large  numbers.  The  smaller  ones  lie  near  the  surface.  The 
larger  are  more  deeply  imbedded,  and  only  approach  the  sur- 
face when  they  are  ready  to  discharge  their  contents.  The 
follicles  have  each  their  own  proper  wall  or  tunic,  derived  from 
the  connective  tissue  of  the  stroma,  and  each  is  lined  by  a  layer 
or  layers  of  granular  epithelium-cells,  and  contains  an  ovum. 
The  granular  layer  of  cells,  closely  lining  the  cavity  of  the 
follicle,  is  termed  the  membrana  granulosa,  but  at  one  or  other 
side  it  is  heaped  up  into  a  mass  of  cells  which  projects  into  the 
cavity  of  the  follicle  and  envelops  the  ovum.  This  mass  of 
cells  which  immediately  surrounds  the  ovum  is  called  the 
discus  proligerus. 

As  the  follicle  matures,  fluid  collects  in  the  cavity,  and, 
increasing  in  amount,  the  follicle  gradually  becomes  larger  and 
more  tense.  It  now  approaches  the  surface  and  begins  to  form 
a  protuberance  like  a  small  boil  upon  the  outside  of  the  ovary. 
Finally  the  wall  of  the  ovary  and  the  wall  of  the  follicle  burst 
at  the  same  point,  and  the  fluid  (liquor  folliculi)  containing  the 
ovum,  with  the  loose,  irregular  mass  of  cells,  the  discus  pro- 
ligerus, clinging  to  it,  is  set  free.  At  the  moment  of  rupture, 
the  ovum  is  received  by  the  Fallopian  tube  and  afterwards  con- 
veyed to  the  uterus.  After  the  follicle  has  discharged  its  con- 
tents, it  has  done  its  work,  and  it  passes  through  a  series  of 
changes  which  are  more  or  less  persistent,  but  eventually  it  is 
obliterated  and  disappears.  Thus  in  the  very  same  ovary  some 
of  the  follicles  are  mature,  or  approaching  maturity ;  others  are 
undergoing  development;  while  others  are  retrograding  and 
disappearing. 

The  ova  are  formed  from  the  germ-epithelium  on  the  surface 
of  the  ovary,  the  cells  of  which  become  enlarged  and  dip  down 
into  the  stroma  in  the  form  of  little  elongated  masses.  From 
these  groups  of  cells  the  Graafian  follicles  and  the  ova  are  pro- 
duced. The  ovum  is  a  highly  developed  cell  about  -j^g-  inch 
in  diameter.  It  has  (1)  a  thick,  surrounding  envelope  or 
membrane,  called  the  vitelline  membrane  or  zona  pellucida ; 
(2)  within  the  membrane  or  cell-wall  is  the  protoplasm  of 
the  cell,  rilled  with  fatty  and  albuminous  granules,  and  usually 


244  ANATOMY  FOR  NURSES.  [CHAP.  XX. 

called  the  vitellus  or  yolk ;  (3)  imbedded  in  the  vitellus  or  yolk 
is  a  transparent,  sharply  outlined  nucleus,  the  germinal  vesicle ; 
and  (4)  in  the  germinal  vesicle  is  a  small  dark  nucleolus,  the 
germinative  spot. 

It  is  impossible  for  us  to  trace  the  growth  and  development 
of  a  fecundated  ovum.  The  subject  is  too  complicated  for  us 
to  attempt  to  describe  it  in  a  book  of  this  kind,  and  we  shall, 
therefore,  content  ourselves  with  briefly  describing  the  first  two 
or  three  steps. 

Soon  after  leaving  the  ovary,  the  germinal  vesicle  and  ger- 
minal spot  in  a  fecundated  ovum  disappear,  and  the  protoplasm 
begins  to  divide  inside  the  vitelline  membrane  into  two  halves, 
in  each  of  which  appears  a  nucleus.  The  halves  divide  into 
quarters,  the  quarters  into  eighths,  and  so  the  subdivision  con- 
tinues until  a  great  number  of  minute  cells  are  produced,  which 
soon  arrange  themselves,  close  to  each  other  like  bricks  in  a 
wall,  upon  the  inner  surface  of  the  vitelline  membrane.  The 
cells  thus  in  close  contact  with  one  another  form  a  membrane, 
called  the  epiblast.  Upon  this  membrane  a  second  one  soon 
appears,  formed  in  the  same  way  and  lining  its  inner  surface. 
This  is  called  the  hypoblast.  Subsequently  a  third  membrane, 
the  mesoblast,  is  developed  between  the  epi-  and  hypoblast,  and 
from  these  three  membranes  all  the  tissues  and  complicated 
structures  of  the  body  are  evolved. 

Upon  the  arrival  of  the  ovum  in  the  uterus,  it  is  grafted 
upon  the  mucous  membrane.  It  usually  lodges  upon  the  upper 
surface  of  the  uterus,  between  two  folds  of  the  mucous  lining, 
which  soon  grow  up  all  around  it,  and,  as  it  were,  bury  the  germ 
in  a  circular  grave.  From  the  thickened  mucous  membrane 
lying  between  the  ovum  and  the  uterine  wall,  the  placenta  is 
ultimately  formed  for  the  nourishment  of  the  embryo. 

The  mammary  glands.  —  The  mammary  gland  is  a  compound 
gland,  formed  of  branching  ducts  ending  in  secretory  recesses. 
The  whole  organ  is  divided  by  connective  tissue  partitions  into 
a  number  of  lobes,  each  of  which  possesses  its  own  excretory 
duct  opening  by  a  separate  orifice  upon  the  surface  of  the 
nipple,  the  gland  being  in  fact  not  a  single  gland,  but  several 
glands  bound  together.  Just  before  opening  on  to  the  nipple, 
each  excretory  duct  is  widened  into  a  flask-shaped  enlarge- 
ment. 


CHAP.  XX.]     FEMALE   GENERATIVE   ORGANS.  245 

The  walls  of  the  ducts  and  of  the  secreting  recesses  are 
formed  of  a  basement  membrane  lined  by  epithelium-cells. 
During  lactation  the  secreting  cells  become  much  enlarged, 
and  fatty  globules  are  formed  within  them.  The  fatty  glob- 
ules appear  to  be  set  free  by  the  breaking  down  of  the  inner 
part  of  the  cell,  the  protoplasm  becoming  dissolved  also,  and 
forming  the  proteid  substances  of  the  milk.  At  the  beginning 
of  lactation  the  cells  are  imperfectly  broken  up,  so  that  numerous 
cells  containing  comparatively  large  masses  of  fat  (the  colostrum 
corpuscles)  appear  in  the  secretion. 

Human  milk  has  a  specific  gravity  of  from  1028  to  1034,  and 
when  quite  fresh  possesses  a  slightly  alkaline  reaction.  Its 
average  composition  in  every  100  parts  is  :  — 

Proteids 2 

Fats 2.75 

Sugar 5 

Salts 0.25 

Water 90 

100 

(Foster.) 


GLOSSAEY. 


Abdu'cens.  [From  the  Lat.  ab,  "from,"  and  duco,  to  "lead."]  A  term  ap- 
plied to  the  sixth  pair  of  cranial  nerves  which  supply  the  external  recti 
(abductor),  muscles  of  the  eye. 

Acetab'ulum.  [From  the  Lat.  acetum,  "  vinegar."]  A  name  given  to  the 
cavity  in  the  os  innominatum,  resembling  in  shape  an  old-fashioned 
vinegar  vessel. 

Acro'mion.  [From  the  Gr.  akron,  "summit,"  and  omos,  the  "shoulder."] 
The  triangular-shaped  process  at  the  summit  of  the  scapula. 

Ad'enpid.  [From  the  Gr.  aden,  a  "gland,"  and  eidos,  "form"  or  "resem- 
blance."] Pertaining  to,,  resembling  a  gland. 

Ad'ipose.     [From  the  Lat.  adeps,  "fat."]     Fatty. 

Afferent.  [From  the  Lat.  ad,  "  to,"  and/ero,  to  "  bear,"  to  "  carry."]  Bear- 
ing or  carrying  inwards,  as  from  the  periphery  to  the  centre. 

Ag'minated.     [From  the  Lat.  agmen,  a  "  multitude,"  a  "  group."]     Arranged 

in  clusters,  grouped. 

.  Albu'min.  [From  the  Lat.  albus,  "  white."]  Animal  albumin  is  the  chief 
solid  ingredient  in  the  white  of  eggs. 

Albuminu'ria.  [A  combination  of  the  words  "albumin"  and  "urine."] 
Presence  of  albumin  in  the  urine. 

Aliment'ary.  [From  the  Lat.  alimentum,  "food."]  Pertaining  to  aliment  or 
food. 

Alimenta'tion.     The  act  of  receiving  nourishment. 

Alve'olar.  [From  the  Lat.  alveolus,  a  "little  hollow."]  Pertaining  to  the 
alveoli,  the  cavities  for  the  reception  of  the  teeth. 

Amoe'ba.  [From  the  Gr.  ameibo,  to  "change."]  A  single-celled,  proto- 
plasmic organism,  which  is  constantly  changing  its  form  by  protrusions 
and  withdrawals  of  its  substance. 

Amce'boid.     Like  an  amoeba. 

Amphiarthro'sis.  [From  the  Gr.  ampho,  "both,"  and  arthron,  a  "joint."] 
A  mixed  articulation ;  one  which  allows  slight  motion. 

Anabol'ic.  [From  the  Gr.  anaballo,  to  "throw"  or  "build  up."]  Pertaining 
to  anabolism,  the  process  by  means  of  which  simpler  elements  are  built 
up  into  move  complex. 

Ansesthe'sia.  [From  the  Gr.  a,  an,  "without,"  and  aisthanomai,  to  "per- 
ceive," to  "  feel."]  A  condition  of  insensibility. 

247 


248  GLOSSARY. 

Anastomo'sis.  [From  the  Gr.  ana,  "  by,"  "  through,"  and  stoma,  a  "  mouth."] 
Communication  of  branches  of  vessels  with  one  another. 

Aor'ta.  [Gr.  aorte  from  ce.ro,  to  "  raise  up."]  The  great  artery  that  rises  up 
from  the  left  ventricle  of  the  heart. 

Aponeuro'sis.  [From  the  Gr.  apo,  "from,"  and  neuron,  a  "nerve."]  A 
fibrous  membranous  expansion  of  a  tendon ;  the  nerves  and  tendons 
were  formerly  thought  to  be  identical  structures,  both  appearing  as 
white  cords. 

Arach'noid.  [From  the  Gr.  arachne,  a  "spider,"  a  "  spider's  web,"  and  eidosj 
"  form  "  or  "  resemblance."]  Resembling  a  web. 

Are'olar.  [From  the  Lat.  areola,  a  "  small  space,"  dim.  of  area.]  A  term 
applied  to  a  connective  tissue  containing  small  spaces. 

Ar'tery.  [From  the  Gr.  aer,  "air,"  and  tereo,  to  "keep."]  Literally,  an 
air-keeper  (it  being  formerly  believed  that  the  arteries  contained  air.) 
A  tube  which  conveys  blood  from  the  heart  to  all  parts  of  the  body. 

Arthro'dia.     [From  the  Gr.  arthron,  a  "  joint."]     A  movable  joint. 

Artic'ular.     Pertaining  to  an  articulation  or  joint. 

Asphyx'ia.  [From  the  Gr.  a,  "  without,"  and  sphyxis,  the  "  pulse."]  Liter- 
ally, without  pulse.  Condition  caused  by  non-oxyge nation  of  the 
blood. 

At'rophy.  [From  the  Gr.  a,  "  without,"  and  trophe,  "  nourishment."]  Wast- 
ing of  a  part  from  lack  of  nutrition. 

Aud'itory.  [From  the  Lat.  audio,  auditum,  to  "hear."]  Pertaining  to  the 
sense  or  organ  of  hearing. 

Aur'icle.  [From  the  dim.  of  Lat.  auris,  the  "ear."]  A  little  ear,  a  term 
applied  to  the  ear-shaped  cavities  of  the  heart. 

Auric'ulo-ventric'ular.     Pertaining  to  the  auricles  and  ventricles  of  the  heart. 

Az'ygos.  [From  the  Gr.  a,  "  without,"  and  zygos,  a  "  yoke."]  Without  a 
feUow. 

Bi'ceps.     [From  the  Lat.  bis,  "  twice,"  and  caput,  the  "  head."]      A  term 

applied  to  muscles  having  a  double  origin  or  two  heads. 
Bicus'pid.     [From  the  Lat.  bis,  "  twice,"  and  cuspis,  the  "  point  of  a  spear."] 

Having  two  points. 

Brach'ial.     [From  the  Lat.  brachium,  the  "  arm."]     Belonging  to  the  arm. 
Buc'cal.     [From   the  Lat.  bucca,  the  "cheek."]     Pertaining  to  the  cheek; 

the  mouth  cavity  formed  chiefly  by  the  cheeks. 
Bur'sal.     [From  the  Gr.  bursa,  a  "  bag."]     Pertaining  to  bursce,  membranous 

sacs. 

Ca'cum.     [From  the  Lat.  ccecus,  "  blind."]     The  blind  gut. 

Ca'lices,  pi.  of  Ca'lyx.     [From  the  Gr.  kalyx,  a  "  cup."]     Anatomists  have 

given  this  name  to  small  cup-like  membranous  canals,  which  surround 

the  papillse  of  the  kidney,  and  open  into  its  pelvis. 
Canalic'ulus,  pi.  Canalic'uli.     [Dim.  of  Lat.  canalis,  a  "channel."]     A  small 

channel  or  vessel. 
Cancellated.     [From  the  Lat.  cancelli,  "lattice-work."]     A   term  used  to 

describe  the  spongy  lattice-work  texture  of  bone. 


GLOSSARY.  249 

Canthus.     [Gr.  Kanthos,  the  "  angle  of  the  eye."]     The  angle  formed  by  the 

junction  of  the  eyelids,  the  internal  being  the  greater,  the  external  the 

lesser,  canthus. 
Cap'illary.     [From  the   Lat.   capillus,   "hair."]      A  minutely  fine    vessel, 

resembling  a  hair  in  size. 
Car'bon.     An  elementary  body,  one  of  the  principal  elements  of  organized 

bodies. 

Carbon'ic  Acid,  C02.     An  acid  gaseous  product. 
Carot'ids.     [Perhaps  from  the  Gr.  karos,  "  stupor,"  because  pressing  on  them 

produces  stupor.]     The  great  arteries  conveying  blood  to  the  head. 
Ca'sein.     [From  the  Lat.  caseus,  "cheese."]     The  albumin  of  milk;    the 

curd  separated  from  milk  by  the  addition  of  rennet,  constituting  the 

basis  of  cheese. 
Caud'a  Equi'na.     [Lat.]     "  Horse-tail."     A  term  applied  to  the  termination 

of  the  spinal  cord,  which  gives  off  a  large  number  of  nerves  which,  when 

unravelled,  resemble  a  horse's  tail. 
Cell'ulose.   Basis  of  vegetable  fibre. 
Cerebellum.     [Dim.  of  Lat.  cerebrum,  the  "  brain."]     The  hinder  and  lower 

part  of  the  brain  ;  the  little  brain. 

Cer'ebrum.     [Lat.  the  "brain."]     Chief  portion  of  brain. 
Ceru'minous.     [From  the  Lat.  cerumen,  "  ear-wax."]     A  term  applied  to  the 

glands  secreting  cerumen,  ear-wax. 
Chon'drin.      [From  the   Gr.   chondros,   "cartilage."]      A  kind   of    gelatin 

obtained  by  boiling  cartilage. 
Chor'dae  Tendin'eae.     [Lat.]     Tendinous  cords. 

Cho'roid.     [From  the  Gr.  chorion,   "  skin,"  and  eidos,  "  form  "  or  "  resem- 
blance."]    A  skin-like  membrane :  the  second  coat  of  the  eye. 
Chyle.     [From  the  Gr.  kylos,  "  juice."]     Milky  fluid  of  intestinal  digestion. 
Chyme.     [From  the  Gr.  kymos,  "juice."]     Food  that  has  undergone  gastric 

but  not  intestinal  digestion.     (Both  chyle  and  chyme  signify  literally 

liquid  or  juice.) 
Cica'trix.     [Lat.  a  "  scar."]     The  mark  or  scar  left  after  the  healing  of  a 

wound. 

Cil'ia.     [Lat.  the  "  eyelashes."]     Hair-like  processes  of  certain  cells. 
Cil'iary.     Pertaining  to  the  cilia. 
Cil'iated.     Provided  with  cilia. 
Circumval'late.     [From  the  Lat.   circumvallo,  "to  surround  with  a  wall."] 

Surrounded  by  a  wall. 
Clav'icle.     [From  the  dim.  of  Lat.  clavis,  a  "  key."]      The  collar-bone,  so 

named  from  its  shape. 
Coc'cyx.     [Lat.   the   "cuckoo."]      The  lower  curved  bone   of    the  spine, 

resembling  a  cuckoo's  bill  in  shape. 
Cocb/lea.     [Lat.   a  "snail,"  a  "snail-shell";    hence,   anything    spiral.]     A 

term  applied  to  a  cavity  of  the  internal  ear. 
Cce'liac.     [From  the  Gr.  koilos,  "hollow."]     Pertaining  to  the  abdominal 

cavity. 
Co'lon.     [Gr.  kolonJ]      That  portion  of  the  large  intestine  which  extends 

from  the  caecum  to  the  rectum. 


250  GLOSSARY. 

Colos'trum.     First  milk  secreted  after  labour. 

Colum'nae  Car'neae.  [Lat.]  "Fleshy  columns";  muscular  projections  in  the 
ventricles  of  the  heart. 

Colum'nar.     Formed  in  columns:  having  the  form  of  a  column. 

Com'missure.  [From  the  Lat.  con,  "  together,"  and  mitto,  missum,  to  "  put."] 
A  joining  or  uniting  together.  Something  which  joins  together. 

Con'cha.  [Lat.  a  "shell."]  A  term  applied  to  the  hollow  portion  of  the 
external  ear. 

Con'dyle.  [From  the  Gr.  kondylos,  a  "knob,"  or  "knuckle."]  An  articu- 
lar eminence. 

Conjunct!' va.  [From  the  Lat.  con,  "  together,"  and  jungo,junctum,  to  "  join."] 
A  term  applied  to  the  delicate  mucous  membrane  which  lines  both  eye- 
lids and  covers  the  external  portion  of  the  eyeball. 

Co'rium.     [Lat.  the  "skin."]     The  deep  layer  of  the  skin  ;   the  derma. 

Cor'nea.  [From  the  Lat.  cornu,  a  "  horn."]  The  transparent  anterior  portion 
of  the  eyeball. 

Coro'nal.     [From  the  Lat.  corona,  a  "  crown."]     Pertaining  to  the  crown. 

Cor'onary.  [From  the  Lat.  corona,  a  "  crown."]  A  term  applied  to  vessels, 
ligaments,  and  nerves  Y^hich  encircle  parts  like  a  crown,  as  the  coronary 
arteries  of  the  heart. 

Cor'pus  Callo'sum.  [Lat.]  "  Callous  body,"  or  substance.  A  name  given  to 
the  hard  substance  uniting  the  cerebral  hemispheres. 

Cor'puscle.  [From  the  dim.  of  Lat.  corpus,  a  "  body."]  A  small  body  or 
particle. 

Cor'tex.     [Lat.  "  bark."]     External  layer  of  kidney :  external  layer  of  brain. 

Cos'tal.     [From  the  Lat.  costa,  a  "rib."]     Pertaining  to  the  ribs. 

Cra'nium.     [Lat.]     The  skull. 

Crassamen'tum.  [From  the  Lat.  crassus,  "thick."]  The  thick  deposit  of 
any  fluid,  particularly  applied  to  a  clot  of  blood. 

Crena'ted.     [From  the  Lat.  crena,  a  "  notch."]     Notched  on  the  edge. 

Crib'riform.  [From  the  Lat.  cribrum,  a  "  sieve,"  and/orma,  "form."]  Perfo- 
rated like  a  sieve. 

Cru'ra  Cer'ebri.  [From  the  Lat.  crus  (pi.  crura),  a  "leg."]  Legs  or  pillars 
of  the  cerebrum. 

Cry'pt.  [From  the  Gr.  krypto,  to  "hide."]  A  secreting  cavity:  a  follicle 
or  glandular  cavity. 

Cu'ticle.  [From  the  dim.  of  Lat.  cutis,  the  "skin."]  A  term  applied  to  the 
upper  or  epidermal  layer  of  the  skin. 

Cu'tis  Ve'ra.     [Lat.]     The  true  skin ;  that  underneath  the  epidermal  layer. 

Cys'tic.  [From  the  Gr.  kystis,  the  "bladder."]  Pertaining  to  a  cyst,  —  * 
bladder  or  sac. 

Decussa'tion.  [From  the  Lat,  decusso,  decussatum,  to  "cross."]  The  cross- 
ing or  running  of  one  portion  athwart  another. 

Del'toid.     Having  a  triangular  shape ;  resembling  the  Greek  letter  A  (delta}. 

)ex'trm.    A  soluble  substance  obtained  from  starch. 

Diabe'tes  Mel'litus.  [From  the  Gr.  dia,  "through,"  baino,  "to  go,"  and 
meh,  "  honey."]  Excessive  flow  of  sugar-containing  urine. 


GLOSSARY.  251 

Dial'ysis.  [From  the  Gr.  dialyo,  to  "  dissolve."]  Separation  of  liquids  by 
membranes. 

Diapede'sis.  [From  the  Gr.  dia,  "  through,"  and  pedao,  to  "  leap,"  to  "  go."] 
Passing  of  the  blood-corpuscles  through  vessel  walls  without  rupture: 
sweating  of  blood. 

Di'aphragm.  [From  the  Gr.  diaphrasso,  to  "divide  in  the  middle  by  a  parti- 
tion."] The  partition  muscle  dividing  the  cavity  of  the  chest  from  that 
of  the  abdomen. 

Diarthro'sis.  [From  the  Gr.  dia,  "  through,"  as  implying  no  impediment, 
and  arthron,  a  "joint."]  A  freely  movable  articulation. 

Dias'tole.     [From  the  Gr.  diastello,  to  "dilate."]     The  dilation  of  the  heart. 

Dip'loe.  [From  the  Gr.  diploo,  to  "double,"  to  "fold."]  The  osseous  tissue 
between  the  tables  of  the  skull. 

Dis'cus  Prolig'erous,  or  germ  disk.  A  term  applied  to  a  mass  of  cell  cling- 
ing to  the  ovum  when  it  is  set  free  from  the  ovary. 

Dis'tal.  [From  the  Lat.  dis,  "  apart,"  and  sto,  to  "  stand."]  Away  from  the 
centre. 

Dor' sal.  [From  the  Lat.  dorsum,  the  "back."]  Pertaining  to  the  back  or 
posterior  part  of  an  organ. 

Duc'tus  Arterio'sus.     [Lat.]     Arterial  duct. 

Duc'tus  Veno'sus.     [Lat.]     Venous  duct. 

Duode'num.  [From  the  Lat.  duodeni,  "twelve  each."]  First  part  of  small 
intestines,  so  called  because  about  twelve  fingers'  breadth  in  length. 

Du'ra  Ma'ter.  [Lat.]  The  "hard  mother,"  called  dura  because  of  its  great 
resistance,  and  mater  because  it  was  formerly  believed  to  give  rise  to 
every  membrane  of  the  body.  The  outer  membrane  of  the  brain  and 
spinal  cord. 

Dyspnce'a.  [From  the  Gr.  dys,  "difficult,"  and  pneo,  to  "breathe."]  -Diffi- 
cult breathing. 

Efferent.  [From  the  Lat.  effero,  to  "  carry  out."]  Bearing  or  carrying  out- 
wards, as  from  the  centre  to  the  periphery. 

Elimination.  [From  the  Lat.  e,  "  out  of,"  and  limen,  liminis,  a  "threshold."] 
The  act  of  expelling  waste  matters.  Eliminate  signifies,  literally,  to 
throw  out  of  doors. 

Em'bryo.  The  ovum  and  product  of  conception  up  to  the  fourth  month, 
when  it  becomes  known  as  the  foetus. 

Enarthro'sis.  [From  the  Gr.  en,  "in,"  and  arthron,  a  "joint."]  An  articu- 
lation in  which  the  head  of  one  bone  is  received  into  the  cavity  of 
another,  and  can  be  moved  in  all  directions. 

Endocardium.  [From  the  Gr.  endon,  "within, "and  kardia,  the  "heart."] 
The  lining  membrane  of  the  heart. 

En'dolymph.  [From  the  Gr.  endon,  "within,"  and  Lat.  lympha,  "water."] 
The  fluid  in  the  membranous  labyrinth  of  the  ear. 

En'siform.  [From  the  Lat.  ensis,  a  "sword,"  and  forma,  "form."]  Shaped 
like  a  sword. 

Ep'iblast.  [From  the  Gr.  epi,  "upon,"  and  blastos,  a  "germ,"  or  "sprout."] 
The  external  or  upper  layer  of  the  germinal  membrane. 


252  GLOSSARY. 

Epidermis.  [From  the  Gr.  epi,  "  upon,"  and  derma,  the  "  skin."]  The  outer 
layer  of  the  skin. 

Epiglot'tis.  [From  the  Gr.  epi,  "  upon,"  and  glottis,  the  "  glottis."]  The  car- 
tilage at  the  root  of  the  tongue  which  forms  a  lid  or  cover  for  the  aper- 
ture of  the  larynx. 

Epithelial.  [From  the  Gr.  epi,  "  upon,"  and  thele,  the  "  nipple."]  Pertain- 
ing to  the  epithelium,  the  cuticle  covering  the  nipple,  or  any  mucous 
membrane.  The  term  epithelium  is  now  applied  to  the  tissue  composed 
of  cells  covering  or  lining  all  surfaces  of  the  body. 

Eth'moid.  [From  the  Gr.  ethmos,  a  "sieve,"  and  eidos,  "form,"  "resem- 
blance."] Sieve-like.  A  bone  of  the  cranium,  part  of  which  is  pierced 
by  a  number  of  holes. 

Eusta'chian  Tube.  A  tube  extending  from  behind  the  soft  palate  to  the 
drum  of  the  ear,  first  described  by  EustacMus. 

Fallo'pian.  A  term  applied  to  tubes  and  ligaments  first  pointed  out  by  the 
anatomist  Fallopius. 

Fas'cia,  pi.  Fas'cise.  [Lat.]  A  bandage,  —  that  which  binds ;  a  membranous 
fibrous  covering. 

Fau'ces.  [Lat.,  pi.  of  faux,  faucis,  the  "throat."]  The  cavity  at  the  back  of 
the  mouth  from  which  the  larynx  and  pharynx  proceed. 

Fem'oral.     Pertaining  to  the  femur. 

Fe'mur.     [Lat.]     The  thigh. 

Fenes'tra.     [Lat.]     A  window. 

Fibrilla,  pi.  Fibrillae.     [Dim.  of  Lat.  fibra,  a  "fibre."]     A  little  fibre. 

Fibrin'ogen.     A  proteid  in  blood  plasma,  main  constituent  of  fibrin. 

Fib'ula.     [Lat.  a  "  clasp."]     The  long  splinter  bone  of  the  leg. 

Filiform.  [From  the  Lat.  filum,  a  "thread,"  and  forma,  "form."]  Thread- 
like. 

Fim'briae.     [Lat.  "threads,"  a  "fringe."]     A  border  or  fringe. 

Fim'briated.     Fringed. 

Fis'sion.  [From  the  Lat.  findo,  fissum,  to  "  cleave."]  A  cleaving  or  break- 
ing up  into  two  parts. 

Foe'tus.     The  child  in  utero  from  the  fifth  month  of  pregnancy  till  birth. 

Follicle.  [From  the  dim.  of  Lat.  follis,  a  "bag."]  A  little  bag;  a  small 
gland. 

Fontanelle'.  [Fr.]  A  little  fountain.  A  term  applied  to  the  membranous 
spaces  between  the  cranial  bones  in  the  new-born  infant,  in  which  the 
pulsation  of  the  blood  in  the  cranial  arteries  was  imagined  to  rise  and 
fall  like  the  water  in  a  fountain. 

Fora'men,  pi.  Foramina.     [Lat.]     An  opening,  hole,  or  aperture. 

Foramen  Mag'num.     [Lat.]     A  large  opening. 

Fora'men  Ovale.     [Lat.]     An  oval  opening. 

Fos'sa,  pi.  Fos'sae.  [From  the  Lat.  fodio,  fossum,  to  "dig."]  A  depression 
or  sinus ;  literally,  a  ditch. 

Fo'vea  Centralis.     [Lat.]     Central  depression. 

Fun'dus.  [Lat.]  The  base  or  bottom  of  any  organ  which  has  an  external 
opening. 


GLOSSARY.  253 

Fun'giform.  [From  the  Lat.  fungus,  a  " mushroom,"  and  forma,  "form."] 
Having  the  shape  of  a  mushroom. 

Funic'ulus.  [Dim.  of  Lat.  funis,  a  "  rope."]  A  little  cord,  or  bundle  of 
aggregated  fibres. 

Fu'siform.  [From  the  Lat.  fusus,  a  "spindle,"  said  forma,  "form."]  Spin- 
dle-shaped. 

Gang'lia,  pi.  of  Ganglion.     [From  the  Gr.  gagglion,  a  "knot."]     A  knot-like 

arrangement  of  nervous  matter  in  the  course  of  a  nerve. 
Gas'tric.     [From  the  Gr.  gaster,  the  "  stomach."]     Pertaining  to  the  stomach. 
Gastrocne'mius.     [From  the  Gr.  gaster,  the  "  belly,"  and  kneme,  the  "  leg."] 

The  6e%-shaped  muscle  of  the  leg. 
Genioglos'sus.     [From  the  Gr.  geneion,  the  "  chin,"  and  glossa,  the  "  tongue."] 

A  muscle  connected  with  the  chin  and  tongue. 

Ginglymus.     [From  the  Gr.  gigglymos,  a  "hinge."]     A  forage-joint. 
Gladi'olus.     [Dim.  of  Lat.  gladius,  a  "sword."]     The  middle  piece  of  the 

sternum. 
Glair'y.     [From  the  Lat.  clarus,  "  clear  " ;  Fr.  clair.~]     Like  the  clear  white 

part  of  an  egg. 

Gle'noid.     [From   the   Gr.   glene,  a  "cavity,"   and   eidos,   "form,"   "resem- 
blance."]    A  name  given  to  a  shallow  cavity. 
Glomer'ulus.     [Dim.  of  Lat.  glomus,  a  "clue  of  thread,"   or   "ball."]     A 

botanical  term   signifying  a  small,  dense,  roundish   cluster :   a  term 

applied  to  the  &a//-like  tuft  of  vessels  in  capsules  of  the  kidneys. 
Glos'so-pharynge'al.     [From  the  Gr.  glossa,  the  "  tongue,"  and  pharygx,  the 

"  pharynx."]     Belonging  to  the  tongue  and  pharynx. 

Glot'tis.     [Gr.  the  "  mouthpiece  of  a  flute."]     The  aperture  of  the  larynx. 
Glute'i,  pi.  of  Glute'us.     [From  the  Greek  gloutoi,  the  "  buttocks."]     The 

muscles  forming  the  buttocks. 
Gly'cogen.     Literally,  producing  glucose.     Animal  starch  found    in    liver, 

which  may  be  changed  into  glucose. 
Graaf  ian  Follicles,  or  Vesicles.     A  term  applied  to  the  hollow  bodies  in  the 

ovaries,  containing  the  ova. 

Gramme.     Unit  of  metric  system,  15.43  grains  troy. 
Gus'tatory.     [From  the  Lat.  gusto,  gustatum,  to  "  taste."]     Belonging  to  the 

sense  of  taste. 

Haemoglo'bin.  [From  the  Gr.  haima,  "  blood,"  and  Lat.  globus,  a  "  globe," 
or  "  globule."]  A  complex  substance  which  forms  the  principal  part  of 
the  blood-globules,  or  red  corpuscles  of  the  blood. 

Haemorrhoi'dal.  [From  the  Gr.  haima,  "  blood,"  and  rheo,  to  "  flow."]  Per- 
taining to  haemorrhoids,  small  tumours  of  the  rectum,  which  frequently 
Need. 

Haver'sian  Canals.  Canals  in  the  bone,  so  called  from  their  discoverer,  Dr. 
Clopton  Havers. 

Hepatic.     [From  the  Gr.  hepar,  hepatos,  the  "  liver."]    Pertaining  to  the  liver. 

Hilum,  sometimes  written  Hilus.  [Lat.]  A  small  fissure,  notch,  or  depres- 
sion. A  term  applied  to  the  concave  part  of  the  kidney. 


254  GLOSSARY. 

Homoge'neous.  [From  the  Gr.  homos,  "the  same,"  and  genos,  "kind."]  Of 
the  same  kind  or  quality  throughout ;  uniform  in  nature,  —  the  reverse 
of  heterogeneous. 

Hu'merus.  [Lat.  the  "shoulder."]  The  arm-bone  which  concurs  in  form- 
ing the  shoulder. 

Hy'aline.  [From  the  Gr.  hyalos,  "glass."]  Glass-like,  resembling  glass  in 
transparency. 

Hy'drogen.  An  elementary  gaseous  substance,  which  in  combination  with 
oxygen  produces  water,  H2O. 

Hy'oid.  [From  the  Gr.  letter  v,  and  eidos,  "  form,"  "  resemblance."]  The 
bone  at  the  root  of  the  tongue,  shaped  like  the  Greek  letter  v. 

Hypermetro'pia.  [From  the  Gr.  hyper,  "  over,"  "  beyond,"  metron,  "  measure," 
and  ops,  the  "  eye."]  Far-sightedness. 

Hyper'trophy.  [From  the  Gr.  hyper,  "  over,"  and  trophe,  "  nourishment."] 
Excessive  growth  ;  thickening  or  enlargement  of  any  part  or  organ. 

Hy'poblast.  [From  the  Gr.  hypo,  "under,"  and  blastos,  a  "sprout"  or 
"  germ."]  The  internal  or  under  layer  of  the  germinal  membrane. 

Hypochon'driac.  [From  the  Gr.  hypo,  "  under,"  and  chondros,  a  "  carti- 
lage."] A  term  applied  to  the  region  of  abdomen  under  the  cartilages 
of  the  false  ribs. 

Hypoglos'sal.  [From  the  Gr.  hypo,  "  under,  "  and  glossa,  the  "  tongue."]  A 
name  given  to  a  nerve  which  terminates  under  the  tongue. 

Il'eum.     [From  the  Gr.  eiled,  to  "  twist."]     The  longest  twisting  portion  of 

the  small  intestine. 
Il'iac.     Pertaining  to  the  ileum. 
Il'ium,  pi.  Il'ia.     [From  the  Gr.  eiled,  to  "  twist."]     The  upper  part  of  the 

os  innominatum;  the  haunch-bone  ;  perhaps  so  called  because  the  crest 

of  the  bone  turns  or  twists  upon  itself. 

Infundib'ula.     [Lat.  pi.  of  infundibulum,  a  "funnel."]    Funnel-shaped  canals. 
In'guinal.     [From  the   Lat.  inguen,  inguinis,  the  "groin."]     Pertaining  to 

the  groin. 
Inos'culate.     [From  the  Lat.  in,  "  into,"  and  osculum,  a  "  little  mouth."]     To 

unite,  to  open  into  each  other. 
Insaliva'tion.     The  process  of  mixing  the  saliva  with  the  food  in  the  act  of 

mastication. 
In'sulate.     [From  the  Lat.  insula,  an  "island."]     To  isolate  or  separate  from 

surroundings. 

Intercellular.     Lying  between  cells. 

Interlob'ular.     That  which  lies  between  the  lobules  of  any  organ. 
Inter'stice.     [From  the  Lat.  inter,  "  between,"  and  sto  or  sisto,  to  "  stand."] 

The  space  which  stands  between  things ;  any  space  or  interval  between 

parts  or  organs. 

Intersti'tial.     Pertaining  to  or  containing  interstices. 
Intralob'ular.     That  which  lies  within  the  lobules  of  any  organ. 
I'ris.     [Lat.  the  "rainbow."]     The  coloured  membrane  suspended  behind 

the  cornea  of  the  eye.     It  receives  its  name  from  the  variety  of  its 

colours. 


GLOSSARY.  255 

Is'chium.  [From  the  Gr.  ischuo,  to  "  support."]  The  lower  portion  of  the 
os  innominatum;  that  upon  which  the  body  is  supported  in  a  sitting 
posture. 

Jeju'num.  [From  the  Lat.  jejunus,  "fasting,"  "empty."]  The  part  of  the 
small  intestine  comprised  between  the  duodenum  and  ileum.  It  has 
been  so  called  because  it  is  almost  always  found  empty  after  death. 

Ju'gular.     [From  the  Lat.  jugulum,  the  "  throat."]     Pertaining  to  the  throat. 

Katabol'ic.  [From  the  Gr.  kataballo,  to  "throw  down."]  Pertaining  to 
kalabolism,  the  process  by  means  of  which  the  more  complex  elements 
are  rendered  more  simple  and  less  complex.  The  opposite  of  anabolism. 

Lach'rymal.     [From  the  Lat.  lachryma,  a  "  tear."]     Belonging  to  the  tears. 

Lac'tation.     [From  the  Lat.  lac,  lactis,  "milk."]     The  period  of  giving  milk. 

Lac'teal.  A  term  applied  to  the  lymphatic  vessels  in  the  intestines  which 
absorb  the  milk-like  fluid,  the  chyle,  from  the  intestines. 

Lac'tic  Acid.     An  acid  obtained  from  sour  milk. 

Lacu'na,  pi.  Lacu'nse.  [Lat.  a  "cavity,"  an  "opening."]  A  little  hollow 
space. 

Lambdoi'dal.  [From  the  Gr.  letter  A  (Lambda"),  and  eidos,  "form,"  "resem- 
blance."] Resembling  the  Gr.  letter  A. 

Lamella,  pi.  Lamel'lae.     [Lat.]     A  thin  plate  or  layer. 

Lar'ynx.  The  upper  part  of  the  air  passage,  between  the  trachea  and  the 
base  of  the  tongue. 

Latis'simus  Dor'si.  [Lat.  superlative  of  latus,  "broad,"  "wide,"  and  dorsum, 
the  "back."]  The  ividest  muscle  of  the  back. 

Lec'ithin.  [From  the  Gr.  lekithos,  the  "  yellow  of  egg."]  A  complex,  fatty 
substance  found  in  the  brain  ;  in  the  yolk  of  eggs. 

Leu'cocyte.  [From  the  Gr.  leukos,  "white,"  and  kytos,  a  "cell."]  A  term 
used  to  denote  the  white  or  pale  corpuscles  in  the  blood  and  lymph. 

Lig'ament.  [From  the  Lat.  ligo,  ligatum,  to  "bind."]  Anything  that  binds 
or  unites. 

Lin'ea  Alba.  [Lat.]  The  white  line  formed  by  the  crossing  of  the  apon- 
eurotic  fibres  in  the  middle  line  of  the  abdomen. 

Lin'ea  Ilio-pectine'a.  [Lat.]  A  line  forming  the  brim  of  the  pelvis,  so 
named  from  subjacent  bone  and  muscle. 

Lob'ule.     [From  the  dim.  of  Lat.  lobus,  a  "  lobe."]     A  small  lobe. 

Lum'bar.     [From  the  Lat.  lumbus,  the  "loin."]     Pertaining  to  the  loins. 

Lymph.  [From  the  Lat.  lympha,  "water."]  A  colourless  fluid,  resembling 
water  in  appearance. 

Lymphat'ic.     Pertaining  to  lymph ;  a  vessel  or  tube  containing  lyrnph. 

Lymphoid.  [From  the  Lat.  lympha,  "water,"  and  Gr.  eidos,  "form,"  "re- 
semblance."] Having  resemblance  to  lymph. 

Mac'ula  Lute'a.     [Lat.]     Yellow  spot. 

Ma'lar.     [From  the  Lat.  mala,  the  "cheek."]     Pertaining  to  the  cheek. 

Malle'olus,  pi.  Malle'oli.       [Dim.  of  Lat.  malleus,  a  "hammer."]     A  name 

given  to  the  pointed  projections  formed  by  the  bones  of  the  leg  at  the 

ankle-joint. 


256  GLOSSARY. 

Malpig'hian  Bod'ies.  [So  called  in  honour  of  Malpighi,  a  celebrated  Italian 
anatomist.]  A  term  applied  to  small  bodies  or  corpuscles  found  in  the 
kidney  and  spleen. 

Manu'brium.  [Lat.  a  "  haft,"  a  "  handle."]  Name  given  to  the  upper  por- 
tion of  the  breast  bone. 

Mar'garin.     One  of  the  three  chief  constituents  of  fat. 

Mas'seter.  [From  the  Gr.  massaomai,  to  "  chew."]  One  of  the  muscles  of 
mastication. 

Mas'toid.  [From  the  Gr.  mastos,  the  "breast,"  and  eidos,  "form,"  "resem- 
blance."] Shaped  like  the  breast. 

Ma'trix.     [Lat.]     The  womb.     Producing  or  containing  substance. 

Max'illary.  [From  the  Lat.  maxilla,  a  "jaw."]  Pertaining  to  the  maxillce 
or  jaws. 

Mea'tus.  [From  the  Lat.  meo,  meatum,  to  "pass."]  A  passage  or 
canal. 

Medul'la  Oblonga'ta.  [Lat.]  The  "  oblong  marrow  " ;  that  portion  of  the 
brain  which  lies  within  the  skull,  upon  the  basilar  process  of  the  occip- 
ital bone. 

Meibo'mian.  A  term  applied  to  the  small  glands  between  the  conjunctiva 
and  tarsal  cartilages,  discovered  by  Meibomius. 

Mes'entery.  [From  the  Gr.  mesos,  "middle,"  and  enteron,  the  "intestine."] 
A  duplicature  of  the  peritoneum  covering  the  small  intestine,  which 
occupies  the  middle  or  centre  of  abdominal  cavity. 

Mes'oblast.  [From  the  Gr.  mesos,  "  middle,"  and  blastos,  a  "  germ "  or 
"  sprout."]  The  middle  layer  of  the  germinal  membrane. 

Mesoco'lon.     A  duplicature  of  the  peritoneum  covering  the  colon. 

Metab'olism.  [From  the  Gr.  metabole,  "change."]  The  changes  taking 
place  in  cells,  whereby  they  become  more  complex  and  contain  more 
force,  or  less  complex  and  contain  less  force.  The  former  is  constructive 
metabolism,  or  anabolism ;  the  latter,  destructive  metabolism,  or  katab- 
olism. 

Metacar'pus.  [From  the  Gr.  meta,  "after,"  and  karpos,  the  "wrist."]  The 
part  of  the  hand  comprised  between  the  wrist  and  fingers. 

Metatar'sus.  [From  the  Gr.  meta,  "  after,"  and  tarsos,  the  "  instep."]  That 
part  of  the  foot  comprised  between  the  instep  and  toes. 

Mi'tral.     Resembling  a  mitre. 

Mo'lar.  [From  the  Lat.  mola,  a  "  mill."]  A  term  applied  to  the  teeth  which 
bruise  or  grind  the  food. 

Molec'ular.     Pertaining  to  molecules. 

Mol'ecule.  [From  the  dim.  of  Lat.  moles,  a  "  mass."]  The  smallest  quantity 
into  which  the  mass  of  any  substance  can  physically  be  divided.  A 
molecule  may  be  chemically  separated  into  two  or  more  atoms. 

Mo'tor  Oc'uli.     [Lat.]     Mover  of  the  eye. 

Moto'rial.     That  which  causes  movement. 

Mu'cin.     The  chief  constituent  of  mucus. 

Mu'cous.     A  term  applied  to  those  tissues  that  secrete  mucus. 

Myocar'dium.  [From  the  Gr.  mys,  myos,  a  "  muscle,"  and  kardia,  the  "  heart."] 
The  muscular  structure  of  the  heart. 


GLOSSARY.  257 

Myo'pia.     [From  the  Gr.  myo,  to  "  contract,"  and  ops,  the  "  eye."]     Near- 
sightedness. 
My'osin.     Chief  proteid  substance  of  muscle. 

Na'ris,  pi.  Na'res.     [Lat.]     A  nostril. 

Weurilem'ma.     [From  the  Gr.  neuron,  a  "nerve,"  and  lemma,  a  "coat"  or 

"  covering."]     Nerve-sheath. 
Ni'trogen.     A  colourless  gas  forming  nearly  four-fifths  of  the  atmosphere : 

the  diluent  of  the  oxygen  in  the  air.     Literally,  that  which  generates 

nitre. 
Nucle'olus,  pi.  Nucle'oli.     [Dim.  of  Lat.  nucleus,  a  "kernel."]     A  smaller 

nucleus  within  the  nucleus. 
Nu'cleus,  pi.  Nu'clei.     [Lat.  a  "kernel."]     A  minute  vesicle  embedded  in 

the  cell  protoplasm. 

Occipi'tal.     [From  the  Lat.  occiput,  occipitis,  the  "back  of  the  head."]     Per- 
taining to  the  occiput,  the  back  part  of  the  head. 
Odon'toid.     [From  the  Gr.  odons,  odontos,  a  "tooth,"  and   eidos,   "form," 

"resemblance."]     Tooth-like. 
(Ede'ma.     [From  the  Gr.  oideo,  to  "swell."]     A  swelling  from  effusion  of 

serous  fluid  into  the  areolar  tissue. 
(Esoph'agus.     [Gr.  oisophagos,  from  oio,  (f ut.)  oiso,  to  "  carry,"  and  phagema, 

"  food."]     The  gullet. 
Olec'ranon.     [From  the  Gr.  olene,  the  "elbow,"  and   kranon,  the  "head."] 

The  head  of  the  elbow. 
O'lein.     [From  the  Lat.  oleum,  "  oil."]     One  of  the  three  chief  constituents 

of  fat.     Oil  (oleum)  signifies  literally,  juice  of  the  olive  (Lat.  olea). 
Olfac'tory.     [From  the  Lat.  olfacio,  olfactum,  to  "smell."]     Belonging  to  the 

sense  of  smell. 
Omen'tum.     [Lat.  "entrails."]     A  duplicature  of  the  peritoneum  with  more 

or  less  fat  interposed. 

Ophthal'mic.     [From  the  Gr.  ophthalmos,  the  "  eye."]     Belonging  to  the  eye. 
Op'tic.     [From  the  Gr.  opfo,  to  "see."]     That  which  relates  to  sight. 
O'ra  Serra'ta.     [Lat.]     Serrated  border. 
Orbicula'ris.     [From  dim.  of  Lat.  orbis,  an  "  orb  "  or  "  circle."]     Name  of  the 

circular  muscles. 
Or'bital.     [From  the  Lat.  orbita,  a  "track,"  "rut  of  a  wheel."]     Pertaining 

to  the  orbit,  the  bony  cavity  in  which  the  eyeball  is  suspended. 
Os,  pi.  O'ra.     [Lat.]     A  mouth. 
Os,  pi.  Ossa.     [Lat.]     A  bone. 
Osmo'sis.     [From  the  Gr.  osmos,  "  impulsion."]     Diffusion  of  liquids  through 

membranes. 
Os'sa  Innomina'ta,   pi.   of  Os   Innomina'tum.     [Lat.]     "  Unnamed  bones." 

The  irregular  bones  of  the  pelvis,  unnamed  on  account  of  their  non-re- 
semblance to  any  known  object. 
Os'teoblasts.     [From  the  Gr.  osteon,  a  "  bone,"  and  blastos,  a   "  germ  "   or 

"  sprout."]     The  germinal  cells  deposited  in  the  development  of  bone. 
O'vum,  pi.  O'va.     [Lat.  an  "  egg."]     The  human  germ  cell. 


258  GLOSSARY. 

Oxida'tion.  The  action  of  oxidizing  a  body;  that  is,  combining  it  with  oxy- 
gen, the  result  of  which  combination  is  an  oxide. 

Ox'ygen.  A  tasteless,  odourless,  colourless  gas,  forming  part  of  the  air, 
water,  etc.,  and  supporting  life  and  combustion. 

Pal'mitm.    A  solid,  crystallizable  substance  of  fat,  found  in  the  nervous  tissue. 

Pal'pebra,  pi.  Pal'pebrae.     [Lat.]     The  eyelid. 

Pan'creas.     A  compound   secreting  gland ;  one  of  the  accessory  organs  of 

nutrition.     The  sweetbread  of  animals. 
Papil'lae.     [Lat.  pi.  of  papilla,  a  "  nipple,"  a  "  pimple."]     Minute  eminences 

on  various  surfaces  of  the  body. 

Paraglob'ulin.     A  proteid  substance  of  the  blood  plasma. 
Pari'etal.     [From  the  Lat.  paries,  parietis,  a  "  wall."]     Pertaining  to  a  wall. 
Parot'id.     [From  the  Gr.  para,  "near,"  and  ous,  otos,  the  "ear."]     The  large 

salivary  gland  under  the  ear. 
Parturi'tion.     [From  the  Lat.  par/urio,  parturitum,  to  "  bring  forth."]     The 

act  of  bringing  forth,  of  giving  birth  to  young. 
Par  Va'gum.     [Lat.]     The  "  wandering  pair."     A  term  sometimes  applied 

to  the  pneumogastric  nerves. 

Patel'la.     [Lat.  "a  little  dish."]     A  small,  fowl-shaped  bone ;  the  knee-pan. 
Pec'toral.     [From  the  Lat.  pectus,  pectoris,  the  "breast."]     Pertaining  to  the 

breast  or  chest. 

Ped'icle.     [From  the  dim.  of  Lat. pes,  pedis,  a  "foot."]     A  stalk. 
Pel'vic.     [From  the  Lat.  pelvis,  a  "  basin."]     Pertaining  to  the  pelois,  the 

basin  or  bony  cavity  forming  the  lower  part  of  the  abdomen. 
Pep'sin.     [From  the  Gr.  pepfo,  to  "  digest."]     A  ferment  principle  in  gastric 

juice,  having  power  to  convert  proteids  into  peptones. 
Pep'tone.     [From  the  Gr.  pepto,  to  "  digest."]     A  term  applied  to  proteid 

material  digested  by  the  action  of  the  digestive  juices. 
Pericar'dium.     [From    the   Gr.  peri,   "about,"   "around,"   and   kardia,  the 

"  heart."]     The  serous  membrane  covering  the  heart. 
Perichon'drium.     [From  the  Gr.  peri,  "about,"  "around,"  and  chondros,  a 

"  cartilage."]     The  serous  membrane  covering  the  cartilages. 
Per'ilymph.     [From  the  Gr.  peri,  "about,"  "  around,"  and  the  Lat.  lympha, 

"  water."]     The  fluid  in  the  osseous,  and  surrounding  the  membranous, 

labyrinth  of  the  ear. 
Perios'teum.    [From  the  Gr.  peri,  "about,"  "  around,"  and  osteon,  a  "  bone."] 

The  membrane  covering  the  bones. 
Peripheral.     [From  the  Gr.  peri,  "  about,"  "  around,"  and  phero,  to  "  bear."] 

Pertaining  to  the  periphery  or  circumference;  that  which  is  away  from 

t.hfi  centre  and  towards  the  circumference. 
Peristal'sis.     [From   the    Gr.    peristelld,    to    "surround,"   to    "compress."] 

Peristaltic  action.     A  term  applied  to  the  peculiar   movement   of   the 

intestines,  like  that  of  a  worm  in  its  progress,  by  which  they  gradually 

propel  their  contents. 
Peritone'um.     [From  the  Gr.  periteino,  to  "stretch  around,"  to  "stretch  all 

over."]     The  serous  membrane  lining  the  walls  and  covering  the  con- 
tents of  the  abdomen. 


GLOSSARY.  259 

Perone'al.  [From  the  Gr.  perone,  the  "  fibula."]  Pertaining  to  the  fibula  ; 
a  term  applied  to  muscles  or  vessels  in  relation  to  the  fibula. 

Pe'trous.     [From  the  Gr.  petra,  a  "  rock."]     Having  the  hardness  of  rock. 

Pey'er's  Glands.  The  clustered  glands  in  the  intestines,  so  named  after  the 
anatomist,  Peyer,  who  well  described  them. 

Phalan'ges.  [Lat.  pi.  of  phalanx,  a  "closely-serried  array  of  soldiers."]  A 
name  given  to  the  small  bones  forming  the  fingers  and  toes,  because 
placed  alongside  one  another  like  a  phalanx. 

Phar'ynx.  [  From  the  Gr.  pharao,  to  "  plough,"  to  "  cleave."]  The  cleft  or 
cavity  forming  the  upper  part  of  the  gullet. 

Phren'ic.  [From  the  Gr.  phren,  the  "diaphragm."]  Pertaining  to  the  dia- 
phragm. 

Pi'a  Ma'ter.  [Lat.  pia  (fern.),  "tender,"  "delicate,"  and  mater,  "mother."] 
The  most  internal  of  the  three  membranes  of  the  brain.  See  Dura 
Mater. 

Pig'ment.     [From  the  Lat.  pigmentum,  "  paint,"  "  colour."]    Colouring  matter. 

Pin'na.  [Lat.  a  "feather"  or  "wing."]  External  cartilaginous  flap  of  the 
ear. 

Placen'ta.  [Lat.  a  "  thin,  flat  cake."]  A  fiat,  circular,  vascular  substance 
which  forms  the  organ  of  nutrition  for  the  foetus  in  utero. 

Plan'tar.  [From  the  Lat.  planta,  the  "sole  of  the  foot."]  Pertaining  to  the 
sole  of  the  foot. 

Plas'ma.  [From  the  Gr.  plasso,  "  to  form."]  A  tenacious  plastic  fluid,  form- 
ing the  coagulating  portion  of  the  blood;  that  in  which  the  blood-cor- 
puscles float;  the  liquor  sanguinis. 

Pleu'ra.  [Gr.  the  "side."]  A  serous  membrane  divided  into  two  portions, 
lining  the  right  and  left  cavities  of  the  chest,  and  reflected  over  each  Inng. 

Plex'us.  [From  the  L&t.plecto,  plexum,  to  "  knit  "  or  "  weave."]  A  network 
of  nerves  or  veins. 

Pneumogas'tric.  [From  the  Gr.  pneumdn,  a  "lung,"  and  gaster,  the  "stom- 
ach."] Pertaining  to  the  lungs  and  stomach. 

Polyhe'dral.  [From  the  Gr.  polys,  "many,"  and  hedra,  a  "  base,"  a  "  side."] 
Many-sided. 

Pons  Varo'lii.  [Lat.]  "Bridge  of  Varolius."  The  white  fibres  which  form 
a  bridge  connecting  the  different  parts  of  the  brain,  first  described  by 
Varolius. 

Poplite'al.  [From  the  Lat.  poples,  poplitis,  the  "  ham,"  the  "back  part  of  the 
knee."]  The  space  behind  the  knee-joint  is  called  the  popliteal  space. 

Prismat'ic.  Resembling  a  prism,  which,  in  optics,  is  a  solid,  glass,  triangu- 
lar-shaped body. 

Prona'tion.  [From  the  Lat.  pronus,  "inclined  forwards."]  The  turning  of 
the  hand  with  the  palm  downwards. 

Prona'tor.     The  group  of  muscles  which  turn  the  hand  palm  downwards. 

Pro'teids.     A  general  term  for  the  albuminoid  constituents  of  the  body. 

Pro'toplasm.  [From  the  Gr.  prdtos,  "  first,"  and  plasxo,  to  "  form."]  Afirst- 
formed  organized  substance  ;  primitive  organic  cell  matter. 

Pseudostom'ata.  [From  the  Gr.  pseudes,  "false,"  and  sloma,  stomatos,  a 
"  mouth."]  False  openings. 


260  GLOSSARY 

Pter'ygoid.  [From  the  Gr.  pteron,  a  "  wing,"  and  eidos,  "  form,"  "  resem- 
blance."] Wing-like. 

Pty'alin.  [From  the  Gr.  pti/alon,  "saliva."]  A  ferment  principle  in  saliva, 
having  power  to  convert  starch  into  sugar. 

Pu'bes,  gen.  Pu'bis.  [Lat.]  The  external  part  of  the  generative  region; 
the  portion  of  the  os  innominatum  forming  the  front  of  the  pelvis. 

Pul'monary.  [From  the  Lat.  pulmo,  pi.  pulmones,  the  "  lungs."]  Relating 
to  the  lungs. 

Pylor'ic.     Pertaining  to  the  pylorus. 

Pylor'us.  [From  the  Gr.  pyle,  a  "gate"  or  "entrance,"  and  ouros,  a 
"  guard."]  The  lower  orifice  of  the  stomach,  furnished  with  a  circular 
valve  which  closes  during  stomach  digestion. 

Pyrex'ia.  [From  the  Gr.  pyresso,  (fut.)  pyrexo,  to  "have  a  fever."]  Eleva- 
tion of  temperature;  fever. 

Quad'riceps.  [From  the  Lat.  quatuor,  "  four,"  and  caput,  the  "  head."]  A 
term  applied  to  the  extensor  muscle  of  the  leg,  having  four  heads  or 
parts. 

Ra'dius.     [Lat.  a  "  rod,"  the  "  spoke  of  a  wheel."]     The  outer  bone  of  the 

fore-arm,  so  called  from  its  shape. 
Rale.     [From  the  Fr.  rdler,  to  "rattle  in  the  throat."]     A  rattling,  bubbling 

sound  attending  the  circulation  of  air  in  the  lungs.     Different  from  the 

murmur  produced  in  health. 
Rec'tus.     [Lat.]     Straight. 

Re'nal.    [From  the  Lat.  ren,  renis,  the  "kidney."]    Pertaining  to  the  kidneys. 
Retic'ular.     [From  the  Lat.  reticulum,  a  "  small  net."]     Resembling  a  small 

net. 
Ret'iform.     [From  the  Lat.  rete,  a  "  net,"  and  forma,  "  form."]     Having  the 

form  or  structure  of  a  net. 
Ret'ina.     [From  the  Lat.  rete,  a  "  net."]     The  most  internal  membrane  of 

the  eye;  the  expansion  of  the  optic  nerve. 
Ri'ma  Glot'tidis.     [Lat.  rima,  a  "chink"  or  "cleft."]     The  opening  of  the 

glottis. 
Ru'gae.     [Lat.  pi.  of  ruga,  a  "wrinkle."]     A  term  applied  to  the  folds  or 

wrinkles  in  the  mucous  membrane,  especially  of  the  stomach  and  vagina. 

Sa'crum.  [Lat.  neut.  of  sacer,  "sacred."]  The  large  triangular  bone  above 
the  coccyx,  so  named  because  it  was  supposed  to  protect  the  organs  con- 
tained in  the  pelvis,  which  were  offered  in  sacrifice  and  considered 
sacred. 

Sag'ittal.     [From  the  Lat.  sagitta,  an  "  arrow."]     Arrow-shaped. 

Sal'ivary.  Pertaining  to  the  saliva,  the  fluid  secreted  by  the  glands  of  the 
mouth. 

Saphe'nous.  [From  the  Gr.  saphes,  "  manifest."]  A  name  given  to  the  two 
large  superficial  veins  of  the  lower  limbs. 

Saponifica'tion.  [From  the  Lat.  sapo,  saponis,  "soap,"  and  facio,  to 
"  make."]  Conversion  into  soap. 


GLOSSARY.  261 

Sarcolem'ma.  [From  the  Gr.  sarx,  sarkos,  "flesh,"  and  lemma,  a  "cover- 
ing."] The  covering  of  the  individual  muscle  fibrils. 

Sar'cous.     [From  the  Gr.  sarx,  sarkos,  "  flesh."]     Fleshy,  belonging  to  flesh. 

Sarto'rius.  [From  the  Lat.  sartor,  a  "tailor."]  The  name  of  the  muscle 
used  in  crossing  the  legs,  as  a  tailor  does  when  he  sits  and  sews. 

Scap'ula.     [Lat]     The  shoulder-blade. 

Sclerot'ic.     [Lat.  scleroticus,  from  Gr.  skleroo,  to  "  harden."]     Hard,  tough. 

Seba'ceous.     A  term  applied  to  glands  secreting  sebum. 

Se'bum  or  Se'vum.  [Lat.  sevum,  "suet."]  A  fatty  secretion  resembling 
suet,  which  lubricates  the  surface  of  the  skin. 

Semilu'nar.  [From  the  Lat.  semis,  "half,"  and  luna,  the  "moon."]  Having 
the  shape  of  a  half-moon. 

Se'rous.     Having  the  nature  of  serum. 

Se'rum.  [Lat.]  The  watery  fluid  separated  from  the  blood  after  coagula- 
tion. 

Ses'amoid.  [From  the  Gr.  sesamon,  a  "seed  of  the  sesamum,"  and  eidos, 
"form,"  "resemblance."]  Resembling  a  grain  of  sesamum.  A  term 
applied  to  the  small  bones  situate  in  the  substance  of  tendons,  near 
certain  joints. 

Sig'moid.  [From  the  Gr.  letter  5,  sigma,  and  eidos,  "form,"  "resemblance."] 
Curved  like  the  letter  S. 

Sole'us.  [From  the  Lat.  solea,  a  "sandal."]  A  name  given  to  a  muscle 
shaped  like  the  sole  of  a  shoe. 

Specific  Grav'ity.  The  comparative  density  or  gravity  of  one  body  con- 
sidered in  relation  to  another  assumed  as  the  standard.  In  measuring 
the  specific  gravity  of  liquids  or  solids,  water  is  usually  taken  as  the 
standard  of  comparison,  being  reckoned  as  a  unit. 

Sphe'noid.  [From  the  Gr.  sphen,  a  "wedge,"  and  eidos,  "form,"  "resem- 
blance."] Like  a  wedge. 

Sphinc'ter.  [From  the  Gr.  sphiggo,  to  "bind  tight,"  to  "  close."]  A  circu- 
lar muscle  which  contracts  the  aperture  to  which  it  is  attached. 

Squa'mous.     [From  the  Lat.  squama,  a  "scale."]     Scale-like. 

Sta'sis.     [From  the  Gr.  stad,  to  "  stop."]     Stagnation  of  the  blood  current. 

Ste'arin.     One  of  the  three  chief  constituents  of  fat. 

Ster'num.     [Lat.]     The  breast-bone. 

Stim'ulus,  pi.  Stim'uli.     [Lat.  a  "  goad."]     Anything  that  excites  to  action. 

Sto'ma,  pi.  Stom'ata.  [From  the  Gr.  stoma,  stomatos,  a  "mouth."]  A 
mouth ;  a  small  opening. 

Strat'ified.  [From  the  Lat.  stratum,  a  "layer,"  and  facio,  to  "make."] 
Formed  or  composed  of  strata  or  layers. 

Stri'ated.  [From  the  Lat.  strio,  striatum,  to  "  make  furrows."]  That  which 
has  stria?,  furrows  or  lines. 

Stro'ma.  [From  the  Gr.  stroma,  a  "  bed."]  The  foundation  or  led  tissue  of 
an  organ. 

Styloglos'sus.  [From  the  Gr.  stylos,  a  "pillar,"  and  glossa,  the  tongue."] 
A  muscle  connected  with  a  pointed  style-like  process  of  the  temporal  bone 
and  the  tongue. 

Subcla'vian.     Under  the  clavicle. 


262  GLOSSARY. 

Subcuta'neous.     [From  the  Lat.  sub,  "  under,"  and  cutis,  the  "skin."]      Under 

the  skin. 
Sudoriferous.     [From  the  Lat.   sudor,   "sweat,"   and  fero,   to  "carry,"  to 

"  bear."]     A  terra  applied  to  the  glands  secreting  sweat. 
Supina'tion.     [From   the  Lat.  supino,  supinatum,  to  "  bend  backwards,"  to 

"place  on   tlie  back."]     The  turning  of  the  hand  with  the  palm  up- 
ward, the  posterior  surface  of  the  hand  being  supine. 
Su'pinators.     The  muscles  which  turn  the  hand  with  the  palm  upward. 
Suprare'nal.     [From  the  Lat.  super,  "over,"  and  ren,  renis,  the  "kidney."] 

Above  the  kidney. 
Su'ture.     [From  the  Lat.  suo,  sutum,  to  "sew  together."]     That  which  is 

sewn  together,  a  seam;  the  seam  uniting  bones  of  the  skull. 
Sym'physis.     [From   the  Gr.  syn,  "together,"   and  phyo,  to  "produce,"  to 

"grow."]     A    union   of   bones,    usually   of   symmetrical   bones   in    the 

median  line,  as  the  pubic  bones  and  bones  of  the  jaw. 
Synarthro'sis.     [From  the  Gr.  syn,  "together,"  and  arthron,  a  "joint."]     A 

form  of  articulation  in  which  the  bones  are  immovably  joined  together. 
Synchondro'sis.     [From  the  Gr.  syn,  "  together,"  and  chondros,  "  cartilage."] 

Union  by  an  intervening  growth  of  cartilage. 
Syndesmo'sis.     [From  the  Gr.  syn,  "  together,"  and  desmos,  a  "  ligament."] 

Union  by  ligaments. 
Syno'via.     [Supposed  to  be  from  the  Gr.  syn,  "  together,"  implying  union 

or  close  resemblance,  and  don,  an  "egg."]      A  fluid  resembling   the 

white  of  an  egg. 

Syno'vial.     Pertaining  to  synovia. 
Syn'tonin.     [From  the  Gr.  synteino,  to  "stretch,"  to  "draw,"  referring  to 

the  peculiar  property  of  muscular  fibre.]     A  name  given  by  Lehman n  to 

a  substance   obtained  from   muscular   fibre   by  the   action   of  dilute 

muriatic  acid. 
Sys'tole.     [From  the  Gr.  systello,  to  "draw  together,"  to  "contract."]     The 

contraction  of  the  heart. 

Tar'sus.  [From  the  Gr.  tarsos,  the  "instep."]  The  instep:  the  cartilage  of 
the  eyelid. 

Ten'do  Achil'lis.  [Lat.]  "  Tendon  of  Achilles."  The  tendon  attached  to  the 
heel,  so  named  because  Achilles  is  supposed  to  have  been  held  by  the 
heel  when  his  mother  dipped  him  in  the  river  Styx  to  render  him  in- 
vulnerable. 

Thorac'ic.  [From  the  Gr.  thorax,  a  "breast-plate,"  the  "breast."]  Pertain- 
ing to  the  thorax. 

Thy'roid.  [From  the  Gr.  thyreos,  an  "oblong  shield,"  and  eidos,  "form," 
"resemblance."]  Resembling  a  shield.  A  name  given  to  an  opening  in 
the  ossa  innominata:  to  the  piece  of  cartilage  forming  the  anterior 
prominence  of  the  larynx:  to  the  gland  placed  in  front  of  the  larynx. 

Tib'ia.  [Lat.  a  "flute"  or  "pipe."]  The  shin-bone,  called  tibia,  f rom  its 
fancied  resemblance  to  a  reed-pipe. 

Tibia'lis  Anti'cus.  [Lat.]  The  muscle  situate  at  the  anterior  part  of  the 
tibia. 


GLOSSARY.  263 

Tibia'lis  Posti'cus.     [Lat.]     The  muscle  situate  at  the  posterior  part  of  the 

tibia. 
Tone.     [Gr.  tonos,  from,  teino,  to  "stretch."]     The  state  of  tension  or  firmness 

proper  to  each  organic  tissue. 
Trabec'ulae.     [Lat.  pi.  of  trabecula,  a  "little   beam."]     A  term  applied  to 

prolongations  of  fibrous  membranes  which  form  septa,  or  partitions. 
Tra'chea.     [Lat.]     The  windpipe. 
Transversa'lis.     [Lat.  from  trans,  "  across,"  and  verto,  versum,  to  "turn, "to 

"direct."]     A  term  applied  to  a  muscle  which  runs  in  a  transverse  direc- 
tion. 
Trape'zius.     A  name  given  to  the  two  upper  superficial  muscles  of  the  back, 

because  together  they  resemble  a  trapezium,  or  diamond-shaped  quad- 
rangle. 
Tri'ceps.     [From  the  Lat.  tres,  "  three,"  and  caput,  the  "head."]     A  term 

applied  to  a  muscle  having  a  triple  origin,  or  three  heads. 
Tri'cuspid.     [From  the  Lat.  tres,  "three,"  and  cuspis,  cutpidis,  a  "point."] 

Having  three  points. 
Trochan'ter.     [From  the  Gr.  trochao,  to  "turn,"  to  "revolve."]     Name  given 

to  two  projections  on  the  upper  extremities  of  the  femur,  which  give 

attachment  to  the  rotator  muscles  of  the  thigh. 
Tryp'sin.     The  ferment  principle  in  pancreatic  juice  which  converts  proteid 

material  into  peptones. 

Tuberos'ity.     [From  the  Lat.  tuber,  tuberis,  a  "swelling."]     A  protuberance. 
Tur'binated.     [Lat.  turbinatu*,  from  turbo,  turbinis,  a  "top."]     Formed  like  a 

top ;  a  name  given  to  the  bones  in  the  outer  wall  of  the  nasal  fossae. 
Tym'panum.     [From  the  Gr.  tympanon,  a  "  drum."]     The  drum  or  hollow 

part  of  the  middle  ear. 

Ul'na.     [Lat.  the  "elbow."]     The  inner  bone  of  the  fore-arm,  the  olecranon 

process  of  which  forms  the  elbow. 
Umbil'icus.     [Lat.  the  "navel."]     A  round  cicatrix  or  scar  in  the  median 

line  of  the  abdomen. 
U'rea.     [From  the  Lat.  urina,  "urine."]     Chief  solid  constituent  of  urine. 

Nitrogenous  product  ot  tissue  decomposition. 
Ure'ter.     [From  the  Gr.  oureo,  to  "pass  urine."]     The  tube  through  which 

the  urine  is  conveyed  from  the  kidney  to  tlie  bladder. 
Ureth'ra.     [From  the  Gr.  oureo,  to  "pass  urine."]     The  canal  through  which 

the  urine  is  conveyed  from  the  bladder  to  the  meatus  urinarins. 
U'vula.     [Dim.  of  Lat.  vva,  a  "grape."]     The  small,  elongated,  fleshy  body 

hanging  from  the  soft  palate. 

Vag'inal.     [From  the  Lat.  vagina,  a  "  sheath."]     Sheath-Yike. 

Val'vulae  Conniven'tes.     [Lat.]     A  name  given  to  transverse  folds  of  the 

mucous  membrane  in  the  small  intestine. 
Vas'a  Vaso'rum.     [Lat.]     "The  vessels  of  the  vessels."     The  small  blood- 

vessels  which  supply  the  walls  of  the  larger  blood-yesxe/s  with  blood. 
Vas'cular.     [From  the  Lat.  vasculum,  a  "little  vessel."]     Relating  to  vessels; 

full  of  vessels. 


264  GLOSSARY. 

Vaso-mo'tor.  [From  the  Lat.  vas,  a  "  vessel,"  and  moveo,  motum,  to  "  move."] 
Causing  motion  to  the  vessels.  Vaso-motor  nerves  cause  contraction  and 
relaxation  of  the  blood-vessels. 

Ve'nae  Ca'vae,  pi.  of  Ve'na  Ca'va.  [Lat.]  "  Hollow  veins."  A  name  given 
to  the  two  great  veins  of  the  body  which  meet  at  the  right  auricle  of  the 
heart. 

Ve'nae  Com'ites.  [Lat.]  "  Attendant  veins."  Veins  which  accompany  the 
arteries. 

Ven'tral.  [From  the  Lat.  venter,  ventris,  the  "belly."]  Belonging  to  the 
belly  cavity. 

Ven'tricle.     [From  the  dim.  of  Lat.  venter,  the  "belly."]     A  small  cavity. 

Ver'miform.  [From  the  Lat.  vermis,  a  "  worm,"  &ud  forma,  "  form."]  Worm- 
shaped. 

Ver'nix  Caseo'sa.  [Lat.]  "  Cheesy  varnish."  The  fatty  varnish  found  on 
the  new-born  infant,  which  is  secreted  by  the  sebaceous  glands  of  the 
skin. 

Ver'tebrae,  pi.  of  Ver'tebra.  [Lat.  from  verto,  to  "  turn."]  The  bones  of  the 
spine. 

Vil'li.  [Lat.  pi.  of  villus,  "shaggy  hair."]  The  conical  projections  on  the 
valvulae  conniventes,  making  the  mucous  membrane  look  shaggy. 

Vis'cera.     [Lat.]     The  internal  organs  of  the  body. 

Vitel'line.  [From  the  Lat.  vitellus,  the  "yolk  of  an  egg."]  A  term  applied 
to  the  yolk  membrane. 

Vetl'lus.     [Lat.  from  vita,  "life."]     The  yolk  of  an  egg. 

Vit'reous.  [From  the  Lat.  vitrum,  "  glass."]  Glass-like.  A  name  applied  to 
the  transparent,  jelly-like  substance  which  fills  the  back  part  of  the  eye- 
ball behind  the  crystalline  lens. 

Vo'mer.  [Lat.  a  "ploughshare."]  The  thin  plate  of  bone  shaped  some- 
what like  a,  ploughshare  which  separates  the  nostrils. 

Vul'va.     The  external  female  genitals. 

Zo'na  Pellu'cida.  [Lat.]  "Pellucid  zone."  The  broad,  transparent  ring 
which  surrounds  the  yolk  in  the  centre  of  the  ovum. 


INDEX. 


Abdomen,  divisions  of,  154. 
Absorbents,  119. 
Absorption,  175. 
Adipose  tissue,  17. 

Adjustment    of   the   eye,    how   accom- 
plished, 233. 
Air-sacs,  133. 
Albumin,  78. 
Alimentary  canal,  153. 
Amoeboid  movement,  77. 
Aorta,  94. 

abdominal,  98. 

thoracic,  98. 
Aponeuroses,  16. 
Appendix  vermiform,  162. 
Aqueous  humour  of  eye,  232. 
Arachnoid  membrane,  204. 
Areolar  tissue,  14. 
Arterial  tension,  111. 
Arteries,  of  head  and  neck,  96. 

of  lower  limb,  101. 

structure  of,  88. 

table  of,  107. 

of  upper  limb,  97. 
Artery,  innominate,  94. 

pulmonary,  106. 
Articulation,  pubic,  35. 
Articulations,  freely  movable,  48. 

immovable,  47. 

slightly  movable,  47. 
Auditory  nerve,  209,  225. 
Auricles  of  the  heart,  84. 

Bile,  172. 
Bladder,  180. 
Blood,  73. 

circulation  of,  109. 

clotting  of,  78. 

fibrin  of,  79. 

functions  of,  73,  80. 


Blood,  plasma  of,  77. 

red  corpuscles  of,  76. 

white  corpuscles  of,  75. 
Blood-vessels,  81. 
Bodily  heat,  196. 
Bone,  cribriform  plate  of  ethmoid,  36. 

development  of,  22. 

ethmoid,  36. 

hyoid,  38. 

structure  of,  20. 
Bones,  23. 

flat,  29. 

irregular,  35. 

long,  24. 

short,  28. 

table  of,  45. 
Brain,  the,  203. 

different  parts  of,  204. 

membranes  of,  203. 

weight  of,  207. 
Bread,  composition  of,  151. 
Bronchial  tubes,  133. 
Bursse,  50. 

Caecum,  162. 

Canal,  alimentary,  153. 

central,  of  spinal  cord,  210. 
Canals,  Haversian,  22. 
Capillaries,  90. 
Carbo-hydrates,  148. 
Carbonic  acid,  excretion  of,  179. 

proportion  of,  in  air,  138. 
Cartilage,  18. 
Cavity,  buccal,  155. 

dorsal,  2. 

pelvic,  43. 

thoracic,  45. 

ventral,  2. 
Cell,  the,  4. 
Cerebellum,  205. 


265 


266 


INDEX. 


Cerebro-spinal  system,  203. 

Cerebrum,  206. 

Chordae  tendineae,  84. 

Choroid  coat  of  eye,  229. 

Chyle,  172. 

Chyme,  171. 

Cilia,  11. 

Circulation,  arterial,  110. 

capillary,  112. 

foetal,  115. 

general,  109. 

portal,  103. 

pulmonary,  109. 

summary  of,  114. 
Coccyx,  40. 
Colon,  162. 
Colour,  224. 
Conjunctiva,  144,  229. 
Connective  tissue,  proper,  14. 
Connective  tissues,  13. 

classification  of,  13. 
Contractility,  muscular,  52,  54. 
Cord,  spinal,  210. 
Corpuscles,  red,  75. 

tactile,  11)1,  216. 

white,  76. 
Cranium,  41. 
Crystalline  lens,  232. 

Development  of  blood-vessels  and  cor- 
puscles, 117. 

of  bone,  22. 

of  muscular  tissue,  55. 
Diaphragm,  65. 
Diastole,  86. 
Diet,  151. 

Digestion,  169,  174. 
Digestive  juices,  bile,  172. 

gastric,  171. 

intestinal,  173. 

pancreatic,  172. 

saliva,  170. 
Diploe,  30. 
Duct,  cystic,  167. 

hepatic,  167. 

nasal,  23(5. 

pancreatic,  162. 

right  lymphatic,  121. 

thoracic,  121. 
Dura  mater,  203. 

Ear,  the,  223. 
Elastic  tissue,  16. 
Elimination,  179. 
Epidermis,  I'.K). 
Epithelial  tissue,  8. 


Epithelium,  simple,  10. 

simple  ciliated,  11. 

simple  columnar,  10. 

simple  glandular,  11. 

simple  pavement,  10. 

stratified,  9. 

transitional,  10. 
Eustachian  tube,  158,  224. 
Eye,  the,  227. 
Eye-brows,  234. 
Eye-lids,  234. 

Fallopian  tubes,  241. 
Fasciae,  16. 
Fats,  148. 

absorption  of,  176. 

digestion  of,  172. 
Fibre,  non-striated  muscular,  54. 

striated  muscular,  53. 
Fibrin,  79. 
Fibro-cartilage,  19. 
Fibrous  tissue,  15. 
Fontanelle,  42. 
Foramen,  thyroid,  35. 
Food,  14(5. 
Food-stuffs,  classified,  147. 

Gall-bladder,  167. 
Ganglia,  203. 

of  spinal  nerves,  212. 

of  sympathetic  system,  214. 
Gastric  juice,  171. 
Glands,  of  Brunner,  161. 

lachrymal,  2M5. 

of  Lieberkuhn,  161. 

lymphatic,  124. 

mammary,  244. 

Meibomian,  235. 

salivary,  156. 

sebaceous,  193. 

secreting,  142. 

solitary,  126. 

sweat,  194. 
Glottis,  the,  130. 
Glycogen, 176. 
Gullet,  the,  158. 

Haemoglobin,  75. 

Hairs,  192. 

Heart,  beat  of  the,  86. 

cavities  of  the,  84. 

position  of  the,  82. 

sounds  of  the,  88. 

structure  of  the,  82. 
Heat,  distribution  of,  197. 

production  of,  196. 


INDEX. 


267 


Heat,  regulation  of,  197. 
Humours  of  the  eye,  228,  232. 

Ileo-orecal  valve,  1(52. 
Impulses,  nervous,  199. 
Inflammation,  113. 
Insensible  perspiration,  195. 
Intestinal  juice,  173. 
Intestine,  large,  1G2. 

small,  1GO. 
Iris,  229. 

Joints,  classification  of,  47. 

movements  of,  49. 

table  of,  HO. 
Juice,  gastric,  171. 

intestinal,  173. 

pancreatic,  172. 

Kidneys,  blood-supply  of,  183. 
position  of,  180. 
structure  of,  182. 

Labyrinth  of  ear,  225. 
Lachrymal  glands,  235. 
Lacteals,  119. 
Larynx,  129. 
Ligamenta  subflava,  16. 
Ligaments,  15. 

annular,  70. 
Light,  231. 
Linea  alba,  61. 
Liver,  position  of  the,  164. 

secretion  of  bile  by  the,  167. 

structure  of  the,  1(55. 
Lungs,  position  of  the,  134. 

structure  of  the,  133. 
Lymph,  73,  121. 

functions  of,  123. 

movements  of,  122. 
Lymphatic  glands,  121. 
Lymphatic  vessels,  119. 

Mammary  glands,  244. 
Mastication,  1(59. 
Meat,  composition  of,  151. 
Medulla  oblongata,  204. 
Medullated  nerve-fibres,  201. 
Membrane,  basement,  145. 

mucous,  144. 

serous,  91. 

synovia!,  50. 
Metabolism,  (5. 
Milk,  composition  of,  151. 
Minerals,  as  food,  149. 
Mouth,  the,  155. 


Muscular  tissue,  52. 

development  of,  55. 

regeneration  of,  56. 
Muscles,  abdominal,  action  of,  64. 

attachment  of,  DO. 

of  head  and  face,  58. 

of  neck  and  trunk,  CO. 

of  lower  extremity,  68. 

table  of  chief,  71. 

of  upper  extremity,  67. 

Nails,  192. 

Nares,  anterior  and  posterior,  221. 

Nerve-cells,  200. 

Nerve-fibres,  200. 

Nerves,  afferent  or  sensory,  202. 

cranial,  207. 

degeneration  of,  216. 

efferent  or  motor,  202. 

regeneration  of,  216. 

spinal,  212. 

termination  of,  216. 
Nervous  system,  202,  215. 
Nervous  tissue,  199. 
Nitrogenous  waste,  excretion  of,  186. 
Nose,  the,  221. 
Nucleus,  7. 

(Edema,  123. 
(Esophagus,  158. 
Organs,  3. 

sensory,  218. 
Osseous  tissue,  20. 
Ovary,  241. 

Ovum,  description  of,  243. 
Oxidation,  139. 

Oxygen,  combination  of,    with    haemo- 
globin, 76,  139. 

Pancreas,  1(53. 
Pancreatic  juice,  172. 
Papilla,  146,  191,  219. 
Patella,  35. 
Pelvis,  43. 
Pepsin,  171. 
Peptone,  171. 
Pericardium,  83. 
Periosteum,  21. 
Peritoneum,  91. 
Perspiration,  194. 
Peyer's  patch,  127. 
Pharynx,  157. 
Pia  mater,  204. 
Plasma  of  the  blood,  77. 
Pleura,  91,  l.T>. 
Pons  Varolii,  205. 


268 


INDEX. 


Pressure,  atmospheric,  135. 
Process,  25. 

alveolar,  38. 

external  malleolus,  28. 

internal  malleolus,  28. 

odontoid,  39. 

olecranon,  26. 
Proteids,  147. 
Protoplasm,  4. 
Ptyalin,  170. 
Pulse,  110. 

Pylorus  of  stomach,  159, 171. 
Pyramids  of  kidney,  182. 
Pyrexia,  197. 

Receptacle  of  the  chyle,  121. 
Rectum,  162. 

Regeneration  of  muscular  tissue,  56. 
Respiration,  129,  135. 

abdominal  or  diaphragmatic,  66. 

costal,  65. 

effect  of,  upon  air  outside  the  body, 
137. 

effect  of,  upon  air  within  the  lungs, 
136. 

effect  of,  upon  the  blood,  138. 
Retina,  230. 
Ribs,  33. 

Sacrum,  40. 

Saliva,  170. 

Salivary  glands,  156. 

Sebaceous  glands,  193. 

Secreting  glands,  142. 

Secretion,  142. 

Sensory  organs,  218. 

Sight,  long  and  near,  233. 

Skeleton,  23. 

Skin,  functions  of  the,  195. 

structure  of  the,  188. 
Skull,  41. 
Sound,  226. 
Sphincter  muscle  of  the  bladder,  181. 

of  rectum,  162. 
Spinal  cord,  210. 
Spine,  38,  40. 
Spleen,  127. 
Stomach,  the,  158. 
Suprarenal  capsules,  187. 
Suture,  47. 
Sweat-glands,  194. 
Symphysis  pubis,  35. 
Synovia,  50. 
System,  cerebro-spinal,  203. 

nervous,  202. 

sympathetic,  214. 
Systole,  86. 


Teeth, 156. 

Temperature  of  blood,  74. 

of  body,  196. 
Tendons,  16. 
Tension,  arterial,  111. 
Thorax,  45. 
Tissue,  adipose,  17. 

areolar,  14. 

cartilaginous,  18. 

connective,  proper,  14. 

elastic,  16. 

epithelial,  8. 

fibrous,  15. 

muscular,  52. 

nervous,  199. 

osseous,  20. 

Tissues,  classification  of,  4. 
Tongue,  the,  219. 
Tonsils,  127. 
Trachea,  131. 
Tympanum,  224. 

Urea,  186. 

Ureters,  180. 

Urethra,  181. 

Urine,  composition  of,  186. 

excretion  of,  185. 

secretion  of,  184. 
Uterus,  238. 
Uvula,  155. 

Vagina,  237. 

Valve,  bicuspid  or  mitral,  85. 

tricuspid,  84. 
Valves  in  veins,  89. 

semilunar,  86. 
Valvulae  conniventes,  160. 
Vein,  portal,  103. 
Veins,  of  head  and  neck,  104. 

of  lower  limb,  105. 

pulmonary,  100. 

right  and  left  azygos,  105. 

structure  of,  89. 

systemic,  103. 

table  of,  107. 

of  upper  limb,  104. 
Vena  cava,  inferior,  106. 

superior,  105. 
Venae  comites,  103. 
Ventricles  of  the  brain,  206. 

of  the  heart,  84. 
Vertebrae,  39. 
Villi,  146,  161. 
Vocal  cords,  130. 

Waste  products,  179. 
Water,  148. 

Zona  pellucida,  243. 


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